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Full text of "NB NBIC 1 (2007): 2009 Addendum to Part 1"

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NOTICE OF INCORPORATION 

United States Legal Document 

J^" All citizens and residents are hereby advised that 
this is a legally binding document duly incorporated by 
reference and that failure to comply with such 
requirements as hereby detailed within may subject you 
to criminal or civil penalties under the law. Ignorance of 
the law shall not excuse noncompliance and it is the 
responsibility of the citizens to inform themselves as to 
the laws that are enacted in the United States of America 
and in the states and cities contained therein. "^& 

* * 

NBIC 2007, National Board Inspection Code, 
Part 1, Installation, 2009 Addenda Release, 
as mandated by the requirements of the States 
of Alabama, Alaska, Arizona, Colorado, Iowa, 
Kansas, Michigan, Missouri, Nebraska, New Jersey, 
North Dakota, Ohio, Oregon, and Utah. 





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National 
Board 

of boiler and 
Pressure Vessel 
Inspectors 




Board 

II C% «?■ •■: ■?- - ': ' ]f p . :' ;| ft 

Code 



Part 1 - Installation 



NATIONAL BOARD INSPECTION CODE 



NOTE: Pages ii through xvi are not part of this 
American National Standard. 



Library of Congress Catalog Card No. 52-44738 

Printed in the United States of America 

All Rights Reserved 

©2009 
The National Board of Boiler and Pressure Vessel Inspectors 

Headquarters 

1055 Crupper Avenue 

Columbus, Ohio 43229-1 1 83 

614.888.8320 

614.847.1828 Fax 

Testing Laboratory 

7437 Pingue Drive 

Worthington, Ohio 43085-1 71 5 

614.888.8320 

614.848.3474 Fax 

Training & Conference Center 

1 065 Crupper Avenue 

Columbus, Ohio 43229-1 1 83 

614.888.8320 

614.847.5542 Fax 

Inspection Training Center 

1 075 Crupper Avenue 

Columbus, Ohio 43229-1 1 83 

614.888.8320 

614.431.3208 Fax 



NATIONAL BOARD INSPECTION CODE 

The National Board of Boiler and Pressure Vessel Inspectors 
Board of Trustees 

R.J. Abenjr. 
Chairman 

J.T. Amato 
First Vice Chairman 

D.J. Jenkins 
Second Vice Chairman 

D.A. Douin 
Seer eta ry Ureas urer 

J.M. Given Jr. 
Member at Large 

G.L. Scribner 
Member at Large 

D.C. Price 
Member at Large 

B. Krasiun 
Member at Large 



Advisory Committee 

G.W. Galanes, RE. 
representing welding industries 

E.J. Hoveke 
representing National Board certificate holders 

L.J. McManamon Jr. 
representing organized labor 

M.J. Pischke 
representing pressure vessel manufacturers 

B.R. Morelock, RE. 
representing boiler and pressure vessel users 

C.E. Perry 
representing boiler manufacturers 

C.G. Schaber 
representing authorized inspection agencies (insurance companies) 



NATIONAL BOARD INSPECTION CODE 



National Board Members 

Alabama Ralph P. Pate 

Alaska Chris Fulton 

Arizona Randall D.Austin 

Arkansas Gary R. Myrick 

California Donald C. Cook 

Colorado Steve Nelson 

Connecticut 

Delaware James B. Harian 

Flonda Michael A. Burns 

Ceor g |a Paul J. Welch 

Hawa " Keith A. Rudolph 

ldaho MikePoulin 

lllinois BennieF. Bailey 

lndiana Dan Willis 

lowa Michael Klosterman 

Kansas Donald J. Jenkins 

Kentucky Rodney Handy 

Louisiana William Owens 

Maine JohnH. Burpee 

Maryland Karl J. Kraft 

Massachusetts Edwards. Kawajr. 

Michigan Robert J. Aben Jr. 

Minnesota JoelT.Amato 

Mississippi Kenneth L.Watson 

Missouri Gary L. Scribner 

Montana Timothy Stewart 

Nebraska Christopher B. Cantrell 

Nevada R oy L p erry 

New Hampshire Wayne Brigham 

New Jersey Milton Washington 

NewVbrk Peter L. Vescio Jr. 

North Carolina Jack M. Given Jr. 

North Dakota Robert Reetz 

Ohio DeanT. Jagger 

Oklahoma Tom Monroe 

Oregon Michael D.Graham 

Pennsylvania Jack A. Davenport 

Rhode Island Benjamin Anthony 

South Carolina Ronald W. Spiker 

South Dakota Howard D. Pfaff 

Tennessee Audrey E. Rogers 

Texa s Anthony P. Jones 

Utah Rick K.Sturm 

Vermont Wesley E. Crider Jr. 

Virginia Edward G. Hilton 

Washington Linda Williamson 

West Virginia John F. Porcella 

Wisconsin Michael J. Verhagen 

Chicago, IL Michael J. Ryan 

Detroit, Ml John E. Bell 

Los Angeles, CA JovieAclaro 

Milwaukee, Wl Randal S. Pucek 

New York, NY William McGivney 

Alberta Ken K.T Lau 

British Columbia John G. Siggers 

Manitoba Terry W Rieger 

New Brunswick Dale E. Ross 

Newfoundland & Labrador E. Dennis Eastman 

Northwest Territories Steve Donovan 

Nova Scotia Peter Dodge 

Nunavut Territory 

Ontario Gilles Lemay 

Prince Edward Island Kenneth Hynes 

Quebec Madiha M. Kotb 

Saskatchewan Brian Krasiun 

Yukon Territory Daniel C. Price 



NATIONAL BDARD INSPECTION CODE 



National Board Inspection Code Committees 



Main Committee 



T. Parks, Chair 

The National Board of Boiler and 

Pressure Vessel Inspectors 


J. Pillow 

Common Arc Corporation 


R. Wielgoszinski, Vice Chair 
Hartford Steam Boiler Inspection and 
Insurance Company of Connecticut 


R. Reetz 

State of North Dakota 


R. Hough, Secretary 

The National Board of Boiler and 

Pressure Vessel Inspectors 


H. Richards 
Southern Company 


S. Bacon 

Conoco Phillips-Ferndale Refinery 


J. Richardson 
Consultant-Dresser, Inc. 


P. Bourgeois 
Travelers 


G. Scribner 
State of Missouri 


D. Canonico 
Canonico & Associates 


J. Sekely 

Wayne Crouse Inc. 


D. Cook 

State of California 


R. Snyder 
ARISE, Inc. 


P. Edwards 

Stone & Webster, Inc. 


S. Staniszewski 

US Department of Transportation 


C. Calanes 

Midwest Generation EME, LLC 


R. Sulzer 

The Babcock & Wilcox Company 


J. Given 

State of North Carolina 


H. Titer 

MIRANT Mid-Atlantic 


F. Hart 

Furmanite Corporation 


J. Yagen 
Dynegy, Inc. 


C. Hopkins 
Seattle Boiler Works 




D. Parrish 
FM Global 





NATIONAL BOARD INSPECTION CODE 



Subcommittee for Installation (Part 1) 



H. Richards, Chair 
Southern Company 

C. Hopkins 
Seattle Boiler Works 

P. Bourgeois 
Travelers 

C. Halley 

ABMA 

S. Konopacki 
Midwest Generation 

B. Moore 

Hartford Steam Boiler Inspection and 

Insurance Company of Connecticut 



H.Tyndall 

Zurich Services Corp. 

C. Scribner 
State of Missouri 

R. Snyder 
ARISE, Inc. 

R. Sulzer 

The Babcock & Wilcox Company 

H. Titer 

MIRANT Mid-Atlantic 

J. Yagen 
Dynegy, Inc. 



Subgroup for Installation (Part 1) 



Boilers 


Pressure Vessels and Piping 


C. Hopkins, Chair 
Seattle Boiler Works 


J. Yagen, Chair 
Dynegy, Inc. 


P. Bourgeois 


H. Richards 


St. Paul Travelers 


Southern Company 


G. Halley, RE. 


G. Scribner 


ABMA 


State of Missouri 


S. Konopacki 
Midwest Generation 


R. Snyder 
ARISE, Inc. 


B. Moore, P.E. 


H. Titer 


Hartford Steam Boiler Inspection 


MIRANT Mid-Atlantic 


H.Tyndall 


H.Tyndall 


Zurich Services Corp. 


Zurich Services Corp. 


G. Scribner 




State of Missouri 




R. Sulzer 




The Babcock & Wilcox Company 





VI 



NATIONAL BOARD INSPECTION CODE 



Subcommittee for Inspection (Part 2) 



D. Cook, Chair 
State of California 

S. Bacon 

Conoco Phillips-Femdale Refinery 

D. Canonico 
Canonico & Associates 

). Getter 
Worthington Cylinders 

C. McRae 

Trinity Industries, Inc. 

V. Newton 
Chubb & Son 

T. Barker 
FM Global 

M. Horbaczewski 
Midwest Generation 



D. Parrish 
FM Global 

R. Reetz 

State of North Dakota 

J. Richardson 
Consultant-Dresser, Inc. 

J. Riley 

Chevron Energy and Technology 

M. Schwartzwalder 
AEP 

S. Staniszewski 

US Department of Transportation 

R. VVacker 
Dupont 

M. Mooney 

Liberty Mutual Insurance 



Subgroup for Inspection (Part 2) 



General Requirements 



J. Getter, Chair 
Worthington Cylinders 

D. Canonico 
Canonico & Associates 

R. Dobbins 
Zurich N.A. 

M. Horbaczewski 
Midwest Generation 

D. Parrish 
FM Global 

J. Richardson 
Consultant-Dresser, Inc. 



S pecific Requirements 

S. Staniszewski 

US Department of Transportation 

S. Bacon 

Conoco Phillips-Femdale Refinery 

D. Cook 

State of California 

R. Dobbins 
Zurich N.A. 

J. Getter 
Worthington Cylinders 

G. McRae 

Trinity Industries, Inc. 

J. Riley 

Chevron Energy and Technology 

M. Schwartzwalder 
AEP 

R. Wacker 
Dupont 



VII 



NATIONAL BOARD INSPECTION CODE 



Subcommi ttee for Repairs and Alterations (Part 3) 



G. Calanes, Chair 

Midwest Generation EME, LLC 

P. Edwards 

Stone & Webster, Inc. 

J. Given 

State of North Carolina 

Wayne Jones 
Arise, Inc. 

J. Larson 

OneBeacon America Insurance Company 



F. Paviovicz 

The Babcock & Wilcox Company 

J. Pillow -Vice Chair 
Common Arc Corporation 

B. Schulte 
NRG Texas, LP 



J. Sekely 

Wayne Crouse Inc. 

M. Webb 
Xcel Energy 



Subgr oup for Rep airs and Alterations (Part 3) 



General Requirements 

P. Edwards, Chair 
Stone & Webster, Inc. 

J. Larson 

One Beacon America Insurance Company 

R. Pulliam 

The Babcock & Wilcox Company 

8. Schulte 

NRG Texas, LP 

M. Webb 
Xcel Energy 

B. Boseo 

Alstom/AP ComPower Inc. 

Brian Morelock 
Eastman Chemical 



S pecific Req uirements 

J. Sekely 

Wayne Crouse Inc. 

G. Galanes 

Midwest Generation EME, LLC 

J. Given 

State of North Carolina 

W. Jones 
ARISE, Inc. 

F. Paviovicz 

The Babcock & Wilcox Company 

J. Pillow, Chair 
Common Arc Corporation 

B. Boseo 

Alstom/AP ComPower Inc. 

Michael Huffman 
American Welding & Tank 



NATIONAL BOARD INSPECTION CODE 



Subcommittee for Pressure Relief Devices (Parts 1, 2, and 3) 


F. Hart, Chair 
Furmanite America Inc. 


R. Donalson 

Tyco Valves and Controls 


A. Cox 
Industrial Value 


K. Fitzsimmons 
Carter Chambers, LLC 


J. Ball 

The National Board of Boiler and 

Pressure Vessel Inspectors 


G. Humphries 
Oxy Vinyls, LP 


M. Brodeur 

International Valve & Instr. Corp. 


R. McCaffrey 
Quality Valve 


S. Cammeresi 
CCR 


T. Patel 

Farris Engineering 


D. DeMichael 
DuPont 





Special Subgroups for Installation, Inspection, and Repairs and Alterations (Parts 1, 2, and 3) 



Locomotive Boilers 




B. Withuhn, Chair 
Smithsonian Institution 


S. Lee 

Union Pacific Railroad 


S. Butler 

Midwest Locomotive & Machine 

Works 


D. McCormack 
Consultant 


D. Conrad 

Valley Railroad Co. 


L. Moedinger 
Strasburg Railroad 


R. Franzen 

Steam Services of America 


R. Reetz 

State of North Dakota 


D. Griner 

Wasatch Railroad Contractors 


G. Scerbo 

Federal Railroad Administration 


S. Jackson 
D&SNG 


R. Schueler 

The National Board of Boiler and Pres- 
sure Vessel Inspectors 


M. Janssen 

Vapor Locomotive Company 


R. Stone 

ABB/Combustion Engineering 




R.Yuill 
Consultant 



Historica! Boilers 



R. Reetz, Chair 
State of North Dakota 


D. Cook 

State of California 


T. Dillion 
Deltak 


B. Babcock 
Consultant 


M. Wahl 
WHSEA 


D. Rupert 
Consultant 


J. Larson 

One Beacon America Insurance 

Company 


S. Bacon 

Conoco Phillips-Ferndale Refinery 


F. Johnson 
PCS Phosphate 





IX 



NATIONAL BOARD INSPECTION CODE 



Special Subgroups for Installation, 


Inspection, and Repairs and Alterations (Parts 1, 2, and 3) 


Graphite 


Fiber-Reinforced Pressure Vessels 


E. Soltow, Chair 

SCL Carbon Croup/SCL Technic 


B. Shelley, Chair 
DuPont 


W. Banker 
Graphite Repairs, Inc 


F. Brown 

The National Board of Boiler and 

Pressure Vessel Inspectors 


F. Brown 

The National Board of Boiler and 

Pressure Vessel Inspectors 


J. Bustillos 

Bustillos and Consultants 


K. Cummins 
Louisville Graphite 


D. Eisberg 

Energy Recovery Inc. 


S. Malone 
Carbone of America 


T. Fowler 
Retired/Spicewood, TX 


M. Minick 

One CIS Insurance 


D. Keeler 

The Dow Chemical Company 


A. Stupica 

SCL Carbon Group/SGL Technic 


R. Lewandowski 

Corrosion Resistant Composites 


T. Bonn 

Carbone of America 


H. Marsh 
Consultant 




J. Richter 

FEMech Engineering 




D. Cook 

State of California 




N. Newhouse 
Lincoln Composites 




D. Hodgkinson 
Consultant 




M. Gorman 
Digital Wave 




R. Crawford 
L&M Fiberglass 




T. Cowley 
Dupont 



NATIONAL BOARD INSPECTION CODE 



National Board Inspection Code 
2007 Edition including 2008 and 2009 Addendum 

Date of Issue — December 31, 2009 

This code was developed under procedures accredited as meeting the criteria for American 
National Standards. The Consensus Committee that approved the code was balanced to ensure 
that individuals from competent and concerned interests had an opportunity to participate. The 
proposed code was made available for public review and comment, which provided an 
opportunity for additional public input from industry, academia, regulatory and jurisdictional 
agencies, and the public-at-large. 

The National Board does not "approve," "rate," or "endorse" any item, construction, 
proprietary device, or activity. 

The National Board does not take any position with respect to the validity of any patent rights 
asserted in connection with any items mentioned in this document, and does not undertake 
to insure anyone utilizing a standard against liability for infringement of any applicable Letters 
Patent, nor assume any such liability. Users of a code are expressly advised that determination 
of the validity of any such patent rights, and the risk of infringement of such rights, is entirely 
their own responsibility. 

Participation by federal agency representative(s) or person(s) affiliated with industry is not to be 
interpreted as government or industry endorsement of this code. 

The National Board accepts responsibility for only those interpretations issued in accordance 
with governing National Board procedures and policies that preclude the issuance of 
interpretations by individual committee members. 

The footnotes in this document are part of this American National Standard. 



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® 



The above National Board symbols are registered with the US Patent Office. 

"National Board" is the abbreviation for The National Board of Boiler and Pressure Vessel 
Inspectors. 

No part of this document may be reproduced in any form, in an electronic retrieval system or 
otherwise, without the prior written permission of the publisher. 



NATIONAL BOARD INSPECTION CODE 



XII 



NATIONAL BOARD INSPECTION CODE 



Foreword 

The National Board of Boiler and Pressure Vessel Inspectors is an organization comprised of 
Chief Inspectors for the states, cities, and territories of the United States and provinces and 
territories of Canada. It is organized for the purpose of promoting greater safety to life and 
property by securing concerted action and maintaining uniformity in post-construction 
activities of pressure-retaining items, thereby ensuring acceptance and interchangeability 
among Jurisdictional authorities responsible for the administration and enforcement of various 
codes and standards. 

In keeping with the principles of promoting safety and maintaining uniformity, the National 
Board originally published The NBIC in 1946, establishing rules for inspection and repairs to 
boilers and pressure vessels. The National Board Inspection Code (NBIC) Committee is charged 
with the responsibility for maintaining and revising the NBIC. In the interest of public safety, 
the NBIC Committee decided, in 1 995, to revise the scope of the NBIC to include rules for 
installation, inspection, and repair or alteration to boilers, pressure vessels, piping, and 
nonmetallic materials. 

In 2007, the NBIC was restructured into three Parts specifically identifying important post- 
construction activities involving safety of pressure-retaining items. This restructuring provides for 
future expansion, transparency, and uniformity, ultimately improving public safety. 

The NBIC Committee's function is to establish rules of safety governing post-construction activities 
for the installation, inspection and repair and alteration of pressure-retaining items, and to interpret 
these rules when questions arise regarding their intent. In formulating the rules, the NBIC 
Committee considers the needs and concerns of individuals and organizations involved in the 
safety of pressure-retaining items. The objective of the rules is to afford reasonably certain 
protection of life and property, so as to give a reasonably long, safe period of usefulness. 
Advancements in design and material and the evidence of experience are recognized. 

The rules established by the NBIC Committee are not to be interpreted as approving, 
recommending, or endorsing any proprietary or specific design, or as limiting in any way an 
organization's freedom to choose any method that conforms to the NBIC rules. 

The NBIC Committee meets regularly to consider revisions of existing rules, formulation of new 
rules, and respond to requests for interpretations. Requests for interpretation must be addressed 
to the NBIC Secretary in writing and must give full particulars in order to receive Committee 
consideration and a written reply. Proposed revisions to the Code resulting from inquiries will 
be presented to the NBIC Committee for appropriate action. 

Proposed revisions to the Code approved by the NBIC Committee are submitted to the 
American National Standards Institute and published on the National Board Web site to 
invite comments from all interested persons. After the allotted time for public review and final 
approval, revisions are published annually in Addenda to the NBIC. 

Organizations or users of pressure-retaining items are cautioned against making use of 
revisions that are less restrictive than former requirements without having assurance that they 
have been accepted by the Jurisdiction where the pressure-retaining item is installed. 



XIII 



NATIONAL BOARD INSPECTION CODE 



The general philosophy underlying the NBIC is to parallel those provisions of the original code 
of construction, as they can be applied to post-construction activities. 

The NBIC does not contain rules to cover all details of post-construction activities. Where 
complete details are not given, it is intended that individuals or organizations, subject to the 
acceptance of the Inspector and Jurisdiction when applicable, provide details for post- 
construction activities that will be as safe as otherwise provided by the rules in the original 
Code of Construction. 

Activities not conforming to the rules of the original code of construction or the NBIC must 
receive specific approval of the Jurisdiction, who may establish requirements for design, 
construction, inspection, testing, and documentation. 

There are instances where the NBIC serves to warn against pitfalls; but the Code is not a hand- 
book, and cannot substitute for education, experience, and sound engineering judgment. 

It is intended that this Edition of the NBIC and any subsequent Addenda not be retroactive. 
Unless the Jurisdiction imposes the use of an earlier edition, the latest effective edition and 
addenda is the governing document. 



NATIONAL BOARD INSPECTION CODE 



Introduction 

It is the purpose of the National Board Inspection Code (NBIC) to maintain the integrity of 
pressure-retaining items by providing rules for installation, and after the items have been 
placed into service, by providing rules for inspection and repair and alteration, thereby 
ensuring that these items may continue to be safely used. 

The NBIC is intended to provide rules, information and guidance to manufacturers, 
Jurisdictions, inspectors, owner-users, installers, contractors, and other individuals and 
organizations performing or involved in post-construction activities, thereby encouraging the 
uniform administration of rules pertaining to pressure-retaining items. 

Scope 

The NBIC recognizes three important areas of post-construction activities where information, 
understanding, and following specific requirements will promote public and personal safety. 
These areas include: 

• Installation 

• Inspection 

• Repairs and Alterations 

The NBIC provides rules, information, and guidance for post-construction activities, but does 
not provide details for all conditions involving pressure-retaining items. Where complete de- 
tails are not provided in this Code, the Code user is advised to seek guidance from the Jurisdic- 
tion and from other technical sources. 

The words shall, should, and may are used throughout the NBIC and have the following intent: 

• Shall - action that is mandatory and required. 

9 Should - indicates a preferred but not mandatory means to accomplish the requirement 

unless specified by others such as the Jurisdiction. 
9 May - permissive, not required or a means to accomplish the specified task. 

Organization 

The NBIC is organized into three Parts to coincide with specific post-construction activities 
involving pressure-retaining items. Each Part provides general and specific rules, information, 
and guidance within each applicable post-construction activity. Other NBIC Parts or other 
published standards may contain additional information or requirements needed to meet the 
rules of the NBIC. Specific references are provided in each Part to direct the user where to find 
this additional information. NBIC Parts are identified as: 

• Part 1, Installation -This Part provides requirements and guidance to ensure all types of 
pressure-retaining items are installed and function properly. Installation includes 
meeting specific safety criteria for construction, materials, design, supports, safety 
devices, operation, testing, and maintenance. 

• Part 2, Inspection -This Part provides information and guidance needed to perform and 
document inspections for all types of pressure-retaining items. This Part includes 
information on personnel safety, non-destructive examination, tests, failure 
mechanisms, types of pressure equipment, fitness for service, risk-based assessments, 
and performance-based standards. 



xv 



NATIDNAL BOARD INSPECTION CODE 



• Part 3, Repairs and Alterations -This Part provides information and guidance to 
perform, verify, and document acceptable repairs or alterations to pressure-retaining 
items regardless of code of construction. Alternative methods for examination, testing, 
heat treatment, etc., are provided when the original code of construction requirements 
cannot be met. Specific acceptable and proven repair methods are also provided. 

Each NBIC Part is divided into major Sections as outlined in the Table of Contents. 

Tables, charts, and figures provide relevant illustrations or supporting information for text 
passages, and are designated with numbers corresponding to the paragraph they illustrate or 
support within each Section. Multiple tables, charts, or figures referenced by the same 
paragraph will have additional letters reflecting the order of reference. Tables, charts, and 
figures are located in or after each major Section within each NBIC Part. 



Text Identification and Numbering 

Each page in the text will be designated in the top header with the publication's name, part 
number, and part title. The numbering sequence for each section begins with the section 
number followed by a dot to further designate major sections (e.g., 1 .1 , 1 .2, 1 .3). Major 
sections are further subdivided using dots to designate subsections within that major section 
(e.g., 1 .1 .1, 1 .2.1, 1 .3.1). Subsections can further be divided as necessary. 

Paragraphs under sections or subsections shall be designated with small letters in parenthesis 
(e.g., a), b), c)) and further subdivided using numbers in parenthesis (e.g., 1), 2), 3)). 
Subdivisions of paragraphs beyond this point will be designated using a hierarchical sequence 
of letters and numbers followed by a dot. 

Example: 2.1 Major Section 

2.1.1 Section 

2.1.2 Section 

2.1.2. Subsection 

a) paragraph 

b) paragraph 

1) subparagraph 

2) subparagraph 

a. subdivisions 

1. subdivisions 

2. subdivisions 

b. subdivisions 

1. subdivisions 

2. subdivisions 

Tables and figures will be designated with the referencing section or subsection identification. 
When more than one table or figure is referenced in the same section or subsection, letters or 
numbers in sequential order will be used following each section or subsection identification. 



XVI 



NATIONAL BOARD INSPECTION CODE 



Supplements 

Supplements are contained in each Part of the NBIC to designate information only pertaining to 
a specific type of pressure-retaining item (e.g., Locomotive Boilers, Historical Boilers, Graphite 
Pressure Vessels.) Supplements follow the same numbering system used for the main text only 
preceded by the Letter "S." Each page of the supplement will identify the supplement number 
and name in the top heading. 



Addenda 

Addenda, which include revisions and additions to this Code, are published annually. Addenda 
are permissive on the date issued and become mandatory six months after the date of issue. 
The addenda will be sent automatically to purchasers of the Code up to the publication of the 
next edition. Every three years the NBIC is published as a new edition that includes that year's 
addenda. 



Interpretations 

On request, the NBIC Committee will render an interpretation of any requirement of this Code. 
Interpretations are provided for each Part and are specific to the Code edition and addenda 
referenced in the interpretation. Interpretations provide information only and are not part of 
this Code. 



Jurisdictiona! Precedence 

Reference is made throughout this Code to the requirements of the "Jurisdiction." Where any 
provision herein presents a direct or implied conflict with any jurisdictional regulation, the 
jurisdictional regulation shall govern. 



Units of Measurement 

Both U.S. customary units and metric units are used in the NBIC. The value stated in U.S. custom- 
ary units or metric units are to be regarded separately as the standard. Within the text, the met- 
ric units are shown in parentheses. In supplement 6, Continued Service and Inspection of DOT 
Transport Tanks, the metric units are shown first with the U.S. customary units shown in parentheses. 

U.S. customary units or metric units may be used with this edition of the NBIC, but one system 
of units shall be used consistently throughout a repair or alteration of pressure-retaining items. 
It is the responsibility of National Board accredited repair organizations to ensure the 
appropriate units are used consistently throughout all phases of work. This includes materials, 
design, procedures, testing, documentation, and stamping. The NBIC policy for metrication is 
outlined in each part of the NBIC. 



Accreditation Programs 

The National Board administers and accredits three specific repair programs 1 as shown below: 

"R" Repairs and Alterations to Pressure-Retaining Items 

"VR" Repairs to Pressure Relief Valves 

"NR" Repair and Replacement Activities for Nuclear Items 



1 Caution, some Jurisdictions may independently administer a program of authorization for organizations to perform repairs and 
alterations within that Jurisdiction. 



XVII 



NATIONAL BOARD INSPECTION CODE 

Part 3, Repairs and Alterations, of the NBIC describes the administrative requirements for the 
accreditation of these repair organizations. 

The National Board also administers and accredits four specific inspection agency programs as 
shown below: 

New Construction 

Criteria for Acceptance of Authorized Inspection Agencies for New Construction 

(NB-360) 
Inservice 

Qualifications and Duties for Authorized Inspection Agencies (AlAs) Performing Inservice 

Inspection Activities and Qualifications for Inspectors of Boilers and Pressure Vessels 

(NB-369) 
Owner-User 

Accreditation of Owner-User Inspection Organizations (OUIO) (NB-371 ) Owners or users 

may be accredited for both a repair and inspection program provided the requirements 

for each accreditation program are met. 
Federal Government 

Qualifications and Duties for Federal Inspection Agencies Performing Inservice Inspection 
Activities (FIAs) (NB-390) " " ' 



These programs can be viewed on the National Board Web site. For questions or further infor- 
mation regarding these programs contact: 

The National Board of Boiler and Pressure Vessel Inspectors 

1055 Crupper Avenue 

Columbus, OH 43229-1 183 

Phone — 614.888.8320 

Fax — 614.847.1828 

Web site — www.nationalboard.org 

Certificates of Authorization for Accreditation Programs 

Any organization seeking an accredited program may apply to the National Board to obtain a 
Certificate of Authorization for the requested scope of activities. A confidential review shall be 
conducted to evaluate the organization's quality system. Upon completion of the evaluation, 
a recommendation will be made to the National Board regarding issuance of a Certificate of 
Authorization. 

Certificate of Authorization scope, issuance, and revisions for National Board accreditation 
programs are specified in the applicable National Board procedures. When the quality system 
requirements of the appropriate accreditation program have been met, a Certificate of 
Authorization and appropriate National Board symbol stamp shall be issued. 



XVIII 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



2.6.3 Drains 21 

2.6.3.1 Connection 21 

2.6.3.2 Pressure Rating 22 

2.6.3.3 Parts 22 

2.7 Operating Systems 22 

2.7.1 Breeching and Dampers 22 

2.7.2 Burners and Stokers 22 

2.7.3 Steam Supply 22 

2.7.4 Condensate and Return 23 

2.7.5 Blowoff 23 

2.8 Controls and Gages 24 

2.8.1 Water " 24 

2.8.2 Pressure Gage 26 

2.8.2.1 Connection 26 

2.8.3 Temperature 26 

2.9 Pressure Relief Valves 26 

2.9.1 Valve Requirements — General 26 

2.9.1.1 Number 26 

2.9.1.2 Location 27 

2.9.1.3 Capacity 27 

2.9.1.4 Set Pressure 29 

2.9.2 Forced-Flow Steam Generator 29 

2.9.3 Superheaters 30 

2.9.4 Economizers 30 

2.9.5 Pressure Reducing Valves 30 

2.9.6 Mounting and Discharge Requirements 31 

2.10 Testing and Acceptance 32 

2.10.1 General 32 

2.10.2 Pressure Test 32 

2.10.3 Nondestructive Examination 32 

2.10.4 System Testing 32 

2.10.5 Final Acceptance 32 

2.10.6 Boiler Installation Report 32 

Section 3 Steam Heating Boilers, Hot-Water Heating Boilers, Hot-Water Supply 

Boilers, and Potable Water Heaters 33 

3.1 Scope 34 

3.2 Definitions 34 

3.2.1 Steam Heating Boilers 34 

3.2.2 Hot-Water Heating and Hot-Water Supply Boilers 34 

3.2.3 Potable Water Heaters 34 

3.3 General Requirements 34 

3.3.1 Supports 34 

3.3.1.1 Methods of Support for Steam Heating, 

Hot-Water Heating, and Hot-Water Supply Boilers 34 

3.3.2 Settings 35 

3.3.3 Structural Steel 36 

3.3.4 Clearances 37 

3.4 Boiler Room Requirements 37 

3.4.1 Exit 37 

3.4.2 Ladders and Runways 37 

3.5 Source Requirements 38 

3.5.1 Water 38 

3.5.2 Fuel 38. 

3.5.3 Electrical 38 

3.5.4 Ventilation and Combustion Air 39 

3.5.5 Lighting 39 

3.5.6 Emergency Valves and Controls 39 

3 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



3.6 Discharge Requirements 39 

3.6.1 Chimney or Stack 39 

3.6.2 Ash Removal 40 

3.6.3 Drains 40 

3.7 Operating Systems 40 

3.7.1 Oil Heaters 40 

3.7.2 Breeching and Dampers 40 

3.7.3 Burners and Stokers 40 

3.7.4 Feedwater, Makeup Water, and Water Supply 40 

3.7.5 Stop Valves 41 

3.7.5.1 Steam Heating, Hot-Water Heating, and 

Hot-Water Supply Boilers 41 

3.7.5.2 Potable Water Heaters 41 

3.7.6 Return Pipe Connections 41 

3.7.7 Bottom Blowoff and Drain Valves 46 

3.7.7.1 Steam Heating, Hot-Water Heating, and 

Hot-Water Supply Boilers 46 

3.7.7.2 Potable Water Heaters 46 

3.7.8 Modular Steam Heating and Hot-Water Heating Boilers 47 

3.7.8.1 Individual Modules 47 

3.7.8.2 Assembled Modular Boilers 47 

3.7.9 Provisions for Thermal Expansion 47 

3.7.9.1 Expansion Tanks and Piping for Steam Heating, 
Hot-Water Heating, Hot-Water Supply Boilers, and 

Potable Water Heaters 47 

3.7.9.2 Expansion Tanks and Piping For Potable Water Heaters 49 

3.8 Instruments, Fittings, and Controls 50 

3.8.1 Steam Heating Boilers 50 

3.8.1.1 Steam Gages 50 

3.8.1 .2 Water Gage Glasses 50 

3.8.1.3 Water Column and Water Level Control Pipes 51 

3.8.1 .4 Pressure Control 51 

3.8.1 .5 Automatic Low-Water Fuel Cutoff and/or Water 

Feeding Device 51 

3.8.1 .6 Modular Steam Heating Boilers 52 

3.8.1 .7 Instruments, Fittings, and Controls Mounted Inside 

Boiler Jackets 52 

3.8.2 Hot-Water Heating or Hot-Water Supply Boilers 52 

3.8.2.1 Pressure or Altitude Gages 52 

3.8.2.2 Thermometers 52 

3.8.2.3 Temperature Control 53 

3.8.2.4 Low-Water Fuel Cutoff 53 

3.8.2.5 Modular Hot-Water Heating Boilers 53 

3.8.2.6 Instruments, Fittings, and Controls Mounted Inside 

Boiler Jackets 53 

3.8.3 Potable Water Heaters 54 

3.8.3.1 Temperature Controls 54 

3.8.3.2 Thermometer 54 

3.9 Pressure-Relieving Valves 54 

3.9.1 Safety Valve Requirements — General 54 

3.9.1 .1 Mounting Safety and Safety ReliefValves for 
Steam Heating, Hot-Water Heating, and 
Hot-Water Supply Boilers 54 

3.9.1 .1 .1 Permissible Mounting 54 

3.9.1 .1 .2 Requirements for Common Connections 

for Two or More Valves 54 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



3.9.1.2 Threaded Connections 55 

3.9.1.3 Prohibited Mountings 55 

3.9.1 .4 Use of Shutoff Valves Prohibited 55 

3.9.1 .5 Safety and Safety ReliefValve Discharge Piping 55 

3.9.1 .6 Temperature and Pressure Safety Relief Valves 55 

3.9.2 Safety Valve Requirements for Steam Boilers 55 

3.9.3 Safety ReliefValve Requirements for Hot-Water Heating or 

Hot-Water Supply Boilers 57 

3.9.4 Safety ReliefValve Requirements for Potable Water Heaters 58 

3.9.4.1 Installation 58 

3.9.4.2 Permissible Mountings 58 

3.9.4.3 Requirements for Common Connection for Two 

or More Valves 59 

3.9.4.4 Threaded Connections 59 

3.9.4.5 Prohibited Mountings 59 

3.9.4.6 Use of Shutoff Valves Prohibited 59 

3.9.4.7 Safety ReliefValve Discharge Piping 59 

3.9.5 Safety and Safety ReliefValves for Tanks and Heat Exchangers 59 

3.9.5.1 Steam to Hot-Water Supply 59 

3.9.5.2 High-Temperature Water to Water Heat Exchanger 59 

3.9.5.3 High-Temperature Water to Steam Heat Exchanger 60 

3.10 Testing and Acceptance 60 

3.10.1 Pressure Test 60 

3.10.2 Final Acceptance 60 

3.10.3 Boiler Installation Report 60 

3.10.4 Tables and Figures 60 

Section 4 Pressure Vessels 63 

4.1 Scope 64 

4.2 Definitions 64 

4.3 General Requirements 64 

4.3.1 Supports 64 

4.3.2 Clearances 64 

4.3.3 Piping 64 

4.3.4 Bolting 64 

4.4 Instruments and Controls 64 

4.4.1 Level Indicating Devices 64 

4.4.2 Pressure Indicating Devices 65 

4.5 Pressure Relief Devices 65 

4.5.1 Device Requirements 65 

4.5.2 Number of Devices 65 

4.5.3 Location 65 

4.5.4 Capacity 65 

4.5.5 Set Pressure 66 

4.5.6 Installation and Discharge Piping Requirements 66 

4.6 Testing and Acceptance 67 

Section 5 Piping 69 

5.1 Scope 70 

5.2 General Requirements 70 

5.2.1 Additions to Existing Piping 70 

5.2.2 Proximity to Other Equipment and Structures 70 

5.2.3 Flanges and Other Non-Welded Joints 70 

5.2.4 Valves 70 

5.2.5 Materials 71 

5.2.6 Hangers and Supports 71 

5.2.7 Protection and Cleaning 71 

5 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



5.2.8 Welding and Brazing 71 

5.2.9 Bolting 71 

5.3 Pressure Relief Devices 71 

5.3.1 Device Requirements 71 

5.3.2 Number of Devices 71 

5.3.3 Location 72 

5.3.4 Capacity 72 

5.3.5 Set Pressure 72 

5.3.6 Inlet and Discharge Piping Requirements 72 

5.4 Examination, Inspection, and Testing 73 

Section 6 Supplements 75 

5.1 Installation of Yankee Dryers (Rotating Cast-iron Pressure Vessels) 

with Finished Shell Outer Surfaces 76 

51.1 Scope 76 

51.2 Assessment of Installation 76 

51.3 Determination of Allowable Operating Parameters 78 

51 .4 ASME Code Primary Membrane Stress Criteria 80 

51 .5 Pressure Testing 80 

51 .6 Nondestructive Examination 81 

5.2 Safety Valves on the Low-Pressure Side of Steam Pressure-Reducing Valves 82 

52.1 Scope 82 

52.2 Safety Valve Capacity 82 

52.3 Calculation of Safety Valve Relieving Capacity 82 

52.4 Steam Flow When Flow Coefficients Are Not Known 83 

52.5 Two-Stage Pressure-Reducing Valve Stations 87 

Section 7 NBIC Policy for Metrication 89 

7.1 General 90 

7.2 Equivalent Rationale 90 

7.3 Procedure for Conversion 90 

7.4 Referencing Tables 91 

Section 8 Preparation of Technical Inquiries to the National Board 

Inspection Code Committee 95 

8.1 Introduction 96 

8.2 Inquiry Format 96 

8.3 Code Revisions or Additions 97 

8.4 Code Interpretations 97 

8.5 Submittals 97 

Section 9 Glossary of Terms 99 

9.1 Definitions 100 

Section 10 NBIC Approved Interpretations 103 

10.1 Scope 104 

10.2 Index of Interpretations 104 

10.3 Subject Index of Interpretations 108 

Section 1 1 Index 1 1 1 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



piping, and other pressure-retaining items 1.4.2 
shall not be operated until the required 
documentation has been provided by the a) 
installer to the owner and the Jurisdiction. 

A07 b) The National Board Commissioned Inspec- 
tor providing inservice inspection for the 
facility in which the pressure-retaining item 
is installed has the following responsibili- 
ties: 

A07 1 ) verify the Bo//er Installation Report (1-1 
Report) has been completed and signed 
by the installer, when required by the b) 
Jurisidication; 

A07 2) verify pressure-retaining items comply 
with the laws and regulations of the 
Jurisdiction governing the specific type 
of boiler or pressure vessel; 

A07 3) verify any repairs or alterations to 
pressure-retaining items, which are 
conducted prior to, or during, the initial 1.4.3 
installation, are in accordance with the 
NBIC; a) 

A07 4) request or assign Jurisdictional identi- 
fication number, when required by the 
Jurisdiction; and 

A07 5) complete and submit the first inservice 
inspection/certificate report to the Juris- 
diction when required by the Jurisdica- b) 
tion. 

A07 Unless otherwise specifically required by 
the Jurisdiction, the duties of the inservice 
inspector do not include the installation's 
compliance to other standards and require- 
ments (environmental, construction, elec- 
trical, undefined industry standards, etc.) 
for which other regulatory agencies have 
authority and responsibility to oversee. 



EQUIPMENT CERTIFICATION 



All boilers, pressure vessels, piping, and 
other pressure-retaining items shall have 
documented certification from the manu- 
facturer indicating that the boiler, pressure 
vessel, piping, or any other pressure-retain- 
ing items comply with the requirements of 
the code of construction. The certification 
shall identify the "Addenda" for a code of 
construction to which all pressure-retaining A09 
items were fabricated. 

Package boilers having external piping 
disassembled and shipped with the boiler 
shall have a method for traceability of the 
disassembled piping that can be verified 
at the time of installation and inspection. 
The manufacturer of the package boiler is 
responsible for determining a method of 
traceability. 



JURISDICTIONAL REVIEW 



The owner shall determine jurisdictional 
requirements (i.e., certificates, permits, 
licenses, etc.) before installing the equip- 
ment. The organization responsible for 
installation shall obtain all permits required 
by the Jurisdiction prior to commencing 
installation. 

The owner shall determine jurisdictional 
requirements (i.e., certificates, permits, li- 
censes, etc.) before operating the equipment. 
The owner shall obtain operating certificates, 
permits, etc., required by the jurisdiction 
prior to commencing operation. 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



1.4.4 INSPECTION 

A07 All boilers, pressure vessels, piping, and other 
pressure-retaining items shall be inspected and 
tested after installation and prior to commenc- 
ing operation. 



1.4.5 BOILER INSTALLATION REPORT 

a) Upon completion, inspection, testing and 
acceptance of the installation, the installer 
shall complete and certify the 6o/7er Instal- 
lation Report (1-1) for all power boilers, 
hot-water heating boilers, steam heating 
boilers, hot-water supply boilers, and po- 
table water heaters. 

b) The Boiler Installation Report (1-1 ) shall be 
submitted as follows: 

1 ) One copy to the owner; and 

2) One copy to the Jurisdiction, if 
required. 



1 D 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



is a guideline for estimating feed pump 
differential: 



Table 2.5.1.3 

Guide for Feedpump Differential 



Boiler Pressure 


Boiler Feedwater 
Pump Discharge 
Pressure 


psig 


(MPa) 


psig 


(MPa) 


200 


(1.4) 


250 


(1.7) 


400 


(2.8) 


475 


(3.3) 


800 


(5.5) 


925 


(6.4) 


1,200 


(8.3) 


1,350 


(9.3) 



b) For forced-flow steam generators with no 
fixed steam or water line, each source 
of feedwater shall be capable of supply- 
ing feedwater to the boiler at a minimum 
pressure equal to the expected maximum 
sustained pressure at the boiler inlet cor- 
responding to operation at maximum de- 
signed steaming capacity with maximum 
allowable pressure at the superheater 
outlet. 

c) Control devices may be installed on feed- 
water piping to protect the pump against 
overpressure. 



2.5.1.4 



VALVES 



b) 



The feedwater piping shall be provided with 
a check valve and a stop valve. The stop 
valve shall be located between the check 
valve and the boiler. 

When two or more boilers are fed from a 
common source, there shall also be a globe 
or regulating valve on the branch to each 
boiler located between the check valve and 
the feedwater source. 



tions are equipped with stop and check 
valves, the stop and check valve in the 
common source may be omitted. 

d) On single boiler-turbine unit installations, 
the boiler feedwater stop valve may be lo- 
cated upstream from the boiler feedwater 
check valve. 

e) If a boiler is equipped with duplicate 
feedwater supply arrangements, each such 
arrangement shall be equipped as required 
by these rules. 

f) A check valve shall not be a substitute for 
a stop valve. 

g) A combination feedwater stop-and-check 
valve in which there is only one seat and 
disk and a valve stem is provided to close 
the valve when the stem is screwed down 
shall be considered only as a stop valve, a 
separate check valve shall be installed. 

h) Whenever globe valves are used on feed- 
water piping, the inlet shall be under the 
disk of the valve. 

i) Stop valves and check valves shall be 
placed on the inlet of economizers or feed- 
water-heating devices. 

j) The recirculating return line for a high 
temperature water boiler shall be provided 
with the stop valve, or valves, required for 
the main discharge outlet on the boiler. 



2.5.2 



FUEL 



Fuel systems, whether firing coal, oil, gas, or 
other substance, shall be installed in accor- 
dance with jurisdictional and environmental re- 
quirements, manufacturer's recommendations, 
and/or industry standards, as applicable. 



c) When the feedwater piping is divided into 
branch connections and all such connec- 



1 9 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



2.5.3 



A09 2.6.3.1 



ELECTRICAL 



WIRING 



All wiring for controls, heat generating appa- 
ratus, and other appurtenances necessary for 
the operation of the boiler or boilers should be 
installed in accordance with the provisions of 
national or international standards and comply 
with the applicable local electrical codes. 



shutdown switch(es) or circuit breaker(s) 
must disconnect all power to the burner 
controls. 

f) For power burners with detached auxil- A09 
iaries, the emergency remote shutdown 
switch(es) or circuit breaker(s) need only 
shut off the fuel input to the burner. 



2.5.3.3 CONTROLS AND HEAT- 
GENERATING APPARATUS 



A09 



A09 2.5.3.2 REMOTE EMERGENCY 

SHUTDOWN SWITCHES 

A09 a) A manually operated remote shutdown 
switch or circuit breaker shall be located 
just outside the boiler room door and 
marked for easy identification. Consider- 
ation should also be given to the type and 
location of the switch to safeguard against 
tampering. 

A09 b) For boiler rooms exceeding 500 sq. ft. 
(46.5 sq. m) floor area or containing one 
or more boilers having a combined fuel 
capacity of 1,000,000 Btu/hr (293kW) or 
more, additional manually operated remote 
emergency shutdown switches shall be lo- 
cated at suitably identified points of egress 
acceptable to the Jurisdiction. 

A09 c) Where a boiler is located indoors in a 
facility and not in a boiler room, a remote 
emergency shutdown switch shall be lo- 
cated within 50 feet of the boiler along the 
primary egress route from the boiler area. 

A09 d) Consideration should be given to the type 
and location of the remote emergency 
shutdown switch(es) to safeguard against 
tampering. Where approved by the Ju- 
risdiction, alternate locations of remote 
emergency switch(es) may be provided. 

A09 e ) For atmospheric-gas burners and for oil 
burners where a fan is on the common shaft 
with the oil pump, the emergency remote 



a) Oil and gas-fired and electrically heated A09 
boilers shall be equipped with suitable 
primary (flame safeguard) safety controls, 
safety limit switches and controls, and 
burners or electric elements as required by 

a nationally or internationally recognized 
standard. 

b) The symbol of the certifying organization A09 
that has investigated such equipment as 
having complied with a nationally rec- 
ognized standard shall be affixed to the 
equipment and shall be considered as 
evidence that the unit was manufactured 

in accordance with that standard. 

c) These devices shall be installed in accor- A09 
dance with jurisdictional and environmen- 
tal requirements, manufacturer's recom- 
mendations, and/or industry standards, as 
applicable. 



2.5.4 VENTILATION AND 

COMBUSTION AIR 

a) The boiler room shall have an adequate air 
supply to permit clean, safe combustion, 
minimize soot formation, and maintain 
a minimum of 19.5% oxygen in the air 
of the boiler room. The combustion and 
ventilation air should be supplied by either 
an unobstructed air opening or by power 
ventilation or fans. 1 



1 Fans - When combustion air is supplied to the boiler by 
an independent duct, with or without the employment of power 
ventilators or fans, the duct shall be sized and installed in ac- 
cordance with the manufacturer's recommendations. However, 
ventilation for the boiler room must still be considered. 



2D 



NATIONAL BOARD INSPECTION CODE * PART 1 



INSTALLATION 



b) Unobstructed air openings shall be sized 2.5.6 
on the basis of 1 sq. in. (650 sq. mm) free 
area per 2000 Btu/hr (586 W) maximum 
fuel input of the combined burners located 
in the boiler room, or as specified in the 
National Fire Protection Association (NFPA) 
standards for oil and gas burning installa- 
tions for the particular job conditions. The 
boiler room air supply openings shall be 
kept clear at all times. 

c) Power ventilators or fans shall be sized 2.6 
on the basis of 0.2 cfm (0.0057 cu meters 

per minute) for each 1000 Btu/hr (293 W) 

of maximum fuel input for the combined 2.6.1 

burners of all boilers located in the boiler 

room. Additional capacity may be required 

for any other fuel-burning equipment in the 

boiler room. 

d) When power ventilators or fans are used 
to supply combustion air, they shall be 
installed with interlock devices so that 2.6.2 
the burners will not operate without an 
adequate number of ventilators/fans in 
operation. 

e) The size of openings specified in 2.5.4(b) 
may be reduced when special engineered 
air supply systems approved by the Jurisdic- 
tion are used. 2.6.3 



EMERGENCY VALVES AND 
CONTROLS 



All emergency shut-off valves and controls shall 
be accessible from a floor, platform, walkway, 
or runway. Accessibility shall mean within a 6 
ft. (1 .8 m) elevation of the standing space and 
not more than 12 in. (305 mm) horizontally 
from the standing space edge. 



DISCHARGE REQUIREMENTS 



CHIMNEY OR STACK 



Chimneys or stacks shall be installed in accor- 
dance with jurisdictional and environmental re- 
quirements, manufacturer's recommendations, 
and/or industry standards, as applicable. 



ASH REMOVAL 



Ash removal systems shall be installed in accor- 
dance with jurisdictional and environmental re- 
quirements, manufacturer's recommendations, 
and/or industry standards, as applicable. 



DRAINS 



f) Care should be taken to ensure that steam 
and water lines are not routed across com- 
bustion air openings, where freezing may 
occur in cold climates. 



2.5.5 



LIGHTING 



The boiler room should be well lighted and it 
should have an emergency light source for use 
in case of power failure. 



2.6.3.1 CONNECTION 

a) Each boiler shall have at least one drain 
pipe fitted with a stop valve at the lowest 
point of the boiler. If the connection is not 
intended for blowoff purposes, a single 
valve is acceptable if it can be locked in 
the closed position or a blank flange can 
be installed downstream of the valve. If 
the connection is intended for blowoff 
purposes, requirements of 2.7.5 shall be 
followed. 



b) For high temperature water boilers, the 
minimum size of the drain pipe shall be 
NPS1 (DN25). 



2 1 



NATIONAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



c) Drain pipes, valves, and fittings within the 
same drain line shall be the same size. 

d) The discharge from the drain shall be piped 
to a safe location. 



2.6.3.2 PRESSURE RATING 

a) When the maximum allowable working 
pressure of the boiler is equal to or less 
than 101 .5 psig (700 kPa), the drain pipe, 
valve, and fittings shall be rated for at least 

A07 1 00 psig (700 kPa) and 220°F (1 04°C). 

b) When the maximum allowable working 
pressure of the boiler exceeds 1 00 psig (700 
kPa), the drain pipe, valve, and fittings shall 
be rated for at least the maximum allowable 
working pressure and temperature of the 
boiler. 



2.6.3.3 



PARTS 



a) When parts (economizers, etc.) are installed 
with a stop valve between the part and the 
boiler or the part cannot be completely 
drained through the drain on the boiler, a 
separate drain shall be installed on each 
such part. These drains shall meet the addi- 
tional requirements of 6.3, as applicable. 

b) Each water column shall have a drain pipe 
fitted with a stop valve at the lowest point of 
the water column. The stop valve shall have 
the capability of being locked in the closed 
position while the boiler is under pressure. 
The minimum size of the drain shall beNPS 
3/4 (DN 20) and all other requirements of 
6.3, as applicable. 



2.7 OPERATING SYSTEMS 



2.7.1 



BREECHING AND DAMPERS 



Breeching and dampers shall be installed in 
accordance with jurisdictional and environ- 
mental requirements, manufacturer's recom- 



mendations, and/or industry standards, as 
applicable. 



2.7.2 



BURNERS AND STOKERS 



Burners and stokers shall be installed in accor- 
dance with jurisdictional and environmental re- 
quirements, manufacturer's recommendations, 
and/or industry standards, as applicable. 



2.7.3 



STEAM SUPPLY 



a) Provisions shall be made for the expansion 
and contraction of steam mains connected 
to boiler(s) so that there shall be no undue 
stress transmitted to the boiler(s). Steam 
reservoirs shall be installed on steam mains 
when heavy pulsations of the steam flow 
causes vibration of the boiler shell plates. 

b) Each discharge outlet of the boiler drum or 
superheater outlet shall be fitted with a stop 
valve located at an accessible point in the 
steam-delivery line and as near the boiler 
nozzle as is convenient and practicable. 
The valve shall be equipped to indicate 
from a distance whether it is closed or open, 
and shall be equipped with a slow-opening 
mechanism. When such outlets are over 
NPS 2 (DN 50), the valve or valves used 
on the connection shall be of the outside 
screw-and-yoke-rising spindle type, so as 
to indicate from a distance by the position 
of its spindle whether it is closed or open 
and the wheel should be carried either on 
the yoke or attached to the spindle. In the 
case of a single boiler and prime mover 
installation, the stop valve may be omitted 
provided the prime mover throttle valve 
is equipped with an indicator to show 
whether the valve is open or closed and is 
designed to withstand the required hydro- 
static test pressure of the boiler. 

c) Stop valves and fittings shall comply with 
the appropriate national standard except 
that austenitic stainless steel is not permit- 
ted for water wetted service. 



22 



NATIONAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



a) 



d) Stop valves and fittings shall be rated for 2.7.4 
the maximum allowable working pressure 
of the boiler and shall be at least rated for 
1 00 psig (700 kPa) at the expected steam 
temperature at the valve or fitting, in ac- 
cordance with the appropriate national 
standard. 

e) The nearest stop valve or valves to the su- 
perheater outlet shall have a pressure rating 
at least equal to the minimum set pressure 

of any safety valve on the superheater 2.7.5 
and at the expected superheated steam 
temperature; or at least equal to 85% of 
the lowest set pressure of any safety valve 
on the boiler drum at the expected steam 
temperature of the superheater outlet, 
whichever is greater. 

f) Ample provision for gravity drain shall be 
provided when a stop valve is so located 
that water or condensation may accumu- 
late. The gravity drain(s) shall be located 
such that the entire steam supply system 
can be drained. 

g) When boilers are connected to a common 
header, the connection from each boiler 
having a manhole opening shall be fitted 
with two stop valves having an ample free- 
blow drain between them. The discharge of 
this drain shall be visible to the operator 
while operating the valve. The stop valves 
shall consist of one stop check valve (set 
next to the boi ler) and a second valve of the 
outside screw-and-yoke type; or two valves 
of the outside screw-and-yoke type. 



CONDENSATE AND RETURN 



Each condensate return pump where practi- 
cable, shall be provided with an automatic 
water level control set to maintain an adequate 
water level in the condensate tank. Condensate 
tanks not constructed in accordance with an 
accepted code or standard shall be vented to 
the atmosphere. 



h) The second steam stop valve shall have 
a pressure rating at least equal to that re- 
quired for the expected steam temperature 
and pressure at the valve; or the pressure 
rating shall be not less than 85% of the low- 
est set pressure of any safety valve on the 
boiler drum and for the expected tempera- 
ture of the steam at the valve, whichever is 
greater. f) 

i) Pressure-reducing valves may be installed 
in the steam supply piping downstream 
from the required stop valve or valves. 



BLOWOFF 



Except for forced-flow steam generators 
with no fixed steam or water line, each 
boiler shall have a blowoff pipe, fitted with 
a stop valve, in direct connection with the 
lowest water space practicable. When the 
maximum allowable working pressure of 
the boiler exceeds 1 00 psig (700 kPa), there 
shall be two valves installed. 



b) The blowoff piping for each electric boiler 
pressure vessel having a nominal water 
content not exceeding 100 gal. (378 I) is re- 
quired to extend through only one valve. 

c) When two valves are required, each bottom 
blowoff pipe shall have two slow-opening 
valves, or one quick-opening valve, at the 
boiler nozzle followed by a slow-opening 
valve. 

d) Two independent slow-opening valves or 
a slow-opening valve and quick-opening 
valve may be combined in one body pro- A09 
vided the combined fitting is the equivalent 
of two independent slow-opening valves or 
a slow-opening valve and a quick-opening 
valve, and the failure of one to operate can- 
not affect the operation of the other. 

e) Straight-run globe valves or valves where 
dams or pockets can exist for the collection A08 
of sediment shall not be used. 



The blowoff valve or valves and the pipe and 
fittings between them and the boiler shall be 
of the same size. The minimum size of pipe 
and fittings shall be NPS 1 (DN 25), except 
boilers with 1 00 sq. ft (9.3 sq. m) of heating 



23 



NATIONAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



surface or less should be NPS 3/4 (DN 20). 
The maximum size of pipe and fittings shall 
not exceed NPS 2-1/2 (DN 65). 

g) For electric boilers, the minimum size of 
blowoff pipes and fittings shall be NPS 1 
(DN 25), except for boilers of 200 kW input 
or less. The minimum size should be NPS 

3/4 (DN 20). 

h) Fittings and valves shall comply with the 
appropriate national standard except that 
austenitic stainless steel and malleable iron 
are not permitted. 

i) When the maximum allowable working 
pressure exceeds 1 00 psig (700 kPa), blow- 
off piping shall be at least Schedule 80 and 
the required valves and fittings shall be 
rated for at least 1 .25 times the maximum 
allowable working pressure of the boiler. 
When the maximum allowable working 
pressure exceeds 900 psig (6.2 MPa), blow- 
off piping shall be at least Schedule 80 and 
the required valves and fittings shall be 
rated for at least the maximum allowable 
working pressure of the boiler plus 225 psi 
(1.6 MPa). 

j) All blowoff piping, when exposed to fur- 
nace heat, shall be protected by fire brick or 
other heat resisting material so constructed 
that the piping may be readily inspected. 

k) On a boiler having multiple blowoff pipes, 
a single master stop valve should be placed 
on the common blowoff pipe from the 
boiler and one stop valve on each indi- 
vidual blowoff. Either the master valve or 
the valves on the individual blowoff lines 
shall be of the slow-opening type. 

I) The discharge of blowoff pipes shall be lo- 
cated so as to prevent injury to personnel. 

m) All waterwalls or water screens that do 
not drain back into the boiler and integral 
economizers forming part of a boiler shall 
be equipped with blowoff piping and valves 
conforming to the requirements of this 
paragraph. 



n) Blowoff piping from a boiler should not 
discharge directly into a sewer. A blowoff 
tank, constructed to the provisions of a 
code of construction acceptable to the Ju- 
risdiction, shall be used where conditions 
do not provide an adequate and safe open 
discharge. 

o) Galvanized pipe shall not be used. 

p) Boiler blowoff systems shall be constructed 
in accordance with the Guide for Blowoff 
Vesse/s(NB-27). 2 

q) Where necessary to install a blowoff tank 
underground, it shall be enclosed in a con- 
crete or brick pit with a removable cover so 
that inspection of the entire shell and heads 
of the tank can be made. 

r) Piping connections used primarily for con- 
tinuous operation, such as deconcentrators 
on continuous blowdown systems, are not 
classed as blowoffs; but the pipe connec- 
tions and all fittings up to and including 
the first shutoff valve shall be equal at least 
to the pressure requirements for the low- 
est set pressure of any safety valve on the 
boiler drum and with the corresponding 
saturated-steam temperature. Further, such 
connections shall not exceed NPS 2-1/2 
(DN 65). 

2.8 CONTROLS AND GAGES 



2.8.1 



WATER 



b) 



Each automatically fired steam boiler shall 
be equipped with at least two low-water fuel 
cutoffs. The water inlet shall not feed water 
into the boiler through a float chamber. 

Each electric steam boiler of the resistance 
element type shall be equipped with an 
automatic low-water cutoff so located as 
to automatically cut off the power supply 



2 The Guide for Blowoff Vessels(NB-27) can be found on the 
National Board Web site, www.nationaiboard.org, under the E- 
Publications/Directories menu button. 



24 



NATIDNAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



to the heating elements before the surface 
of the water falls below the visible part of 
the glass. No low-water cutoff is required 
for electrode-type boilers. 

c) Designs embodying a float and float bowl 
shali have a vertical straightaway drainpipe 
at the lowest point in the water equalizing 
pipe connections, by which the bowl and 
the equalizing pipe can be flushed and the 
device tested. 

d) The water column shall be directly connect- 
ed to the boiler. Outlet connections (except 
for damper regulator, feedwater regulator, 
low-water fuel cutoff, drains, steam gages, 
or such apparatus that does not permit the 
escape of an appreciable amount of steam 
or water) should not be placed on the pip- 
ing that connects the water column to the 
boiler. 

e) Straight-run globe valves of the ordinary 
type shall not be used on piping that con- 
nects the water column to the boiler. Where 
water columns are 7 ft. (2.1 m) or more 
above the floor level, adequate means for 
operating gage cocks or blowing out the 
water glass shall be provided. 

f) When automatic shutoff valves are used 
on piping that connects the water column 
to the boiler, they shall conform to the re- 
quirements of the code of construction for 
the boiler. 

g) When shutoff valves are used on the con- 
nections to a water column, they shall be 
either outside-screw-and-yoke or lever- 
lifting-type gate valves or stop cocks with 
levers permanently fastened thereto and 
marked in line with their passage, or of such 
other through-flow constructions to prevent 
stoppage by deposits of sediment and to 
indicate by the position of the operating 
mechanism whether they are in open or 
closed position; and such valves or cocks 
shall be locked or sealed open. 

h) Each steam boiler having a fixed waterline 
shall have at least one water-gage glass 



except that boilers operated at pressures 
over 400 psig (2.8 MPa) shall be provided 
with two water-gage glasses that may be 
connected to a single water column or con- 
nected directly to the drum. The gage glass 
connections and pipe connection shall be 
not less than NPS 1/2 (DN 1 5). Each water- 
gage glass shall be equipped with a valved 
drain. 

i) Electric steam boilers shall have at least one 
water-gage glass. On electrode-type electric 
boilers, the gage glass shall be located as 
to indicate the water levels both at startup 
and maximum steam load conditions, as 
established by the boiler manufacturer. 
On resistance element type electric steam 
boilers, the lowest visible part of the gage 
glass shall be located at least 1 in. (25 mm) 
above the lowest permissible water level 
established by the boiler manufacturer. 

j) The lowest visible part of the water-gage 
glass shall be at least 2 in. (50 mm) above 
the lowest permissible water level estab- 
lished by the boiler manufacturer. 

k) For all installations where the water-gage 
glass or glasses are not easily viewed by the 
operator, consideration should be given to 
install a method of remote transmission of 
the water level to the operating floor. 

I) Boilers of the horizontal firetube type shall 
be so set that when the water is at the lowest 
reading in the water gage glass, there shall 
be at least 3 in. (75 mm) of water over the 
highest point of the tubes, flues, or crown 
sheet. 

m) Each water-gage glass shall be equipped 
with a top and a bottom shutoff valve of 
such through-flow construction as to pre- 
vent blockage by deposits of sediment and 
to indicate by the position of the operating 
mechanism whether they are in the open 
or closed position. The pressure-tempera- 
ture rating shall be at least equal to that of 
the lowest set pressure of any safety valve 
on the boiler drum and the corresponding 
saturated steam temperature. 



25 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



A07 2.8.2 



PRESSURE GAGE 



2.9 



PRESSURE RELIEF VALVES 



a) Each steam boiler shall have a pressure 
gage connected to the steam space or to 
the steam connection to the water column. 
When a pressure-reducing valve is installed 
in the steam supply piping, a pressure gage 
shall be installed on the low pressure side 
of the pressure-reducing valve. 

b) The dial range shall not be less than 1.5 
times or no greater than two times the 

A09 pressure at which the lowest pressue-relief 
valve is set. 



A07 



2.8.2.1 



CONNECTION 



a) For a steam boiler the gage or connection 
shall contain a siphon or equivalent device 
that will develop and maintain a water seal 
that will prevent steam from entering the 
gage tube. A valve or cock shall be placed 
in the gage connection adjacent to the 
gage. An additional valve or cock should be 
located near the boiler providing it is locked 
or sealed in the open position. No other 
shut-off valves shall be located between 
the gage and the boiler. 

b) Pressure gage connections shall be suitable 
for the maximum allowable working pres- 
sure and temperature, but if the temperature 
exceeds 406°F (208°C), brass or copper 
pipe or tubing shall not be used. The con- 
nections to the boiler, except for the siphon, 
if used, shall not be less than NFS 1/4 (DN 
8). Where steel or wrought iron pipe or 
tubing is used, it shall not be less than 1/2 
in. (1 3 mm) inside diameter. The minimum 
size of a siphon, if used, shall be 1/4 in. (6 
mm) inside diameter. 



2.9.1 VALVE REQUIREMENTS — 

GENERAL 

a) Safety valves are designed to relieve steam. 

b) Safety relief valves are valves designed to 
relieve either steam or water, depending on 
the application. 

c) Safety and safety relief valves are to be 
manufactured in accordance with a na- 
tional or international standard. 

d) Deadweight or weighted-lever pressure- 
relieving valves shall not be used. 

e) For high temperature water boilers, safety 
relief valves shall have a closed bonnet, 
and safety relief valve bodies shall not be 
constructed of cast iron. 

f) Safety and safety relief valves with an inlet 
connection greater than NPS 3 (DN 80) 
used for pressure greater than 1 5 psig (1 03 
kPa), shall have a flange inlet connection 
or a welding-end inlet connection. The 
dimensions of flanges subjected to boiler 
pressure shall conform to the applicable 
standards. 

g) When a safety or safety rel ief valve is exposed 
to outdoor elements that may affect operation 
of the valve, it is permissible to shield the 
valve with acover. The cover shall be properly 
vented and arranged to permit servicing and 
normal operation of the valve. 



2.9.1.1 



NUMBER 



2.8.3 



TEMPERATURE 



Each high temperature water boiler shall have 
a temperature gage or other reporting device 
located to provide an accurate representation of 
the temperature at or near the boiler outlet. 



At least one National Board capacity certified 
safety or safety relief valve shall be installed on 
the boiler. If the boiler has more than 500 sq. ft. 
(46 sq. m.) of heating surface, or if an electric 
boiler has a power input of more than 3.76 mil- 
lion BTU/hr (1 1 00 kW), two or more National 
Board capacity certified safety or safety relief 
valves shall be installed. 



A07 



zs 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



^m * Jf * I 4^1 



LOCATION 



a) Safety or safety relief valves shall be placed 
on, or as close as physically possible, to the 
boiler proper. 

b) Safety or safety relief valves shall not be 
placed on the feedline. 

c) Safety or safety relief valves shall be con- 
nected to the boiler independent of any 
other connection without any unnecessary 
intervening pipe or fittings. Such interven- 
ing pipe or fittings shall not be longer than 
the face-to-face dimension of the corre- 
sponding tee fitting of the same diameter 
and pressure rating as listed in the appli- 
cable standards. 



2.9.1.3 CAPACITY 

a) The pressure-relieving valve capacity for 
each boiler shall be such that the valve or 
valves will discharge all the steam that can 
be generated by the boiler without allowing 
the pressure to rise more than 6% above 
the highest pressure at which any valve is 
set and in no case to more than 6% above 
the maximum allowable working pressure 
of the boiler. 

b) The minimum relieving capacity for other 
than electric boilers and forced-flow steam 
generators with no fixed steam line and 
waterline shall be estimated for the boiler 
and waterwall heating surfaces as given in 
Table 2.9.1.3, but in no case should the 
minimum relieving capacity be less than 
the maximum designed steaming capacity 
as determined by the manufacturer. 

c) The required relieving capacity in pounds 
per hour of the safety or safety relief valves 
on a high temperature water boiler shall 
be determined by dividing the maximum 
output in Btu at the boiler nozzle obtained 
by the firing of any fuel for which the unit 
is designed by one thousand. 



d) The minimum safety or safety relief valve 
relieving capacity for electric boilers is 3.5 
Ibs/hr/kW (1 .6 kg/hr/kW) input. 

e) If the safety or safety relief valve capacity 
cannot be computed, or if it is desirable 
to prove the computations, it should be 
checked by any one of the following meth- 
ods; and if found insufficient, additional 
relieving capacity shall be provided: 

1) By performing an accumulation test, 
that is, by shutting off all other steam 
discharge outlets from the boiler and 
forcing the fires to the maximum. This 
method should not be used on a boiler 
with a superheater or reheater or on a 
high temperature water boiler. 

2) By measuring the maximum amount of 
fuel that can be burned and computing 
the corresponding evaporative capacity 
upon the basis of the heating value of 
the fuel. 

3) By determining the maximum evapo- 
rative capacity by measuring the feed- 
water. The sum of the safety valve ca- 
pacities marked on the valves shall be 
equal to or greater than the maximum 
evaporative capacity of the boiler. This 
method should not be used on high 
temperature water boilers. 



27 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



Table 2.9.1.3 - Minimum Pounds of steam 
per hour per square foot of 
Heating Surface 1 lb steam/hr/sq.ft (kg/hr/ 
sq m) 



A08 



Firetube Boilers 



Boiler heating surface 



Watertube Boilers 



A08 
A08 

A08 



A07 
A08 



A08 



A08 



hand-fired 



stoker-fired 



oil, gas, or pulverized fuel-fired 



5(24) 



7(34) 



(39) 



Waterwall heating surface 



hand-fired 



stoker-fired 



oil, gas, or pulverized fuel-fired 



(39) 



1 (49) 



14 



Copper-finned watertubes 



hand-fired 



stoker-fired 



oil, gas, or pulverized fuel-fired 



6(29) 



(39) 



10(49) 



(39) 



12 (59) 



16(78) 



4(20) 



5(24) 
6(29) 



NOTES: 

• When a boiler is fired only by a gas having a heat value not in excess of 200 Btu/cu.ft.(7.5MJ/cu. m), the mini- 
mum relieving capacity should be based on the values given for hand-fired boilers above. 

• The heating surface shall be computed for that side of the boiler surface exposed to the products of combustion, 
exclusive of the superheating surface. In computing the heating surface for this purpose only the tubes, fireboxes,' 
shells, tubesheets, and the projected area of headers need to be considered, except that for vertical firetube steam 
boilers, only that portion of the tube surface up to the middle gage cock is to be computed. 

• For firetube boiler units exceeding 8000 Btu/ft. 2 (9085 J/cm. 2 ) (total fuel Btu (J) Input divided by total heating 
surface), the factor from the table will be increased by 1 (4.88) for every 1000 Btu/ft. 2 (1136J/cm. 2 ) above 
8000 Btu/ft. 2 (9085 J/cm. 2 ) For units less than 7000 Btu/ft. 2 (7950 J/cm. 2 ), the factor from the table will be 
decreased by 1 (7950 J/cm. 2 ). 

• For watertube boiler units exceeding 1 6000 Btu/ft. 2 (1 81 70 J/cm. 2 )(total fuel BTU input divided by the total 
heating surface) the factor from the table will be increased by 1 (4.88) for every 1 000 Btu/ft. 2 (1136 J/cm. 2 ) 
above 1 6000 Btu/ft. 2 (1 81 70 J/cm. 2 ). For units with less than 1 5000 Btu/ft. 2 (1 7034 J/cm. 2 ), the factor in the 
table will be decreased by 1 (4.88) for every 1 000 Btu/ft. 2 (1136 J/cm. 2 ) below 1 5000 Btu/ft. 2 (1 7034 J/cm. 2 ). 



2B 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



2.9.1.4 SET PRESSURE 

One or more safety or safety relief valves on 
the boiler proper shall be set at or below the 
maximum allowable working pressure. If ad- 
ditional valves are used, the highest pressure 
setting shall not exceed the maximum allow- 
able working pressure by more than 3%. The 
complete range of pressure settings of all the 
safety relief valves on a boiler shall not exceed 
10% of the highest pressure to which any valve 
is set. Pressure setting of safety relief valves on 
high temperature water boilers may exceed 
this 10% range. 



2.9.2 FORCED-FLOW STEAM 

GENERATOR 

For a forced-flow steam generator with no 
fixed steamline and waterline, equipped with 
automatic controls and protective interlocks 
responsive to steam pressure, safety valves 
A08 may be provided in accordance with the above 
paragraphs identified in 2.9.1 or the follow- 
ing protection against overpressure shall be 
provided: 

a) One or more power-actuated pressure-re- 
lieving valves shall be provided in direct 
communication with the boiler when the 
boiler is under pressure and shall receive 
a control impulse to open when the maxi- 
mum allowable working pressure at the 
superheater outlet is exceeded. The total 
combined relieving capacity of the power- 
actuated pressure-relieving valves shall be 
not less than 10% of the maximum design 
steaming capacity of the boiler under any 
operating condition as determined by the 
manufacturer. The valves shall be located 
in the pressure part system where they will 
relieve the overpressure. An isolating stop 
valve of the outside-screw-and-yoke type 
should be installed between the power- 
actuating pressure-relieving valve and 
the boiler to permit repairs provided an 
alternate power-actuated pressure-relieving 
valve of the same capacity is so installed 



as to be in direct communication with the 
boiler. 

b) Spring-loaded safety valves shall be pro- 
vided having a total combined relieving ca- 
pacity, including that of the power-actuated 
pressure-relieving valve, of not less than 
1 00% of the maximum designed steaming 
capacity of the boiler, as determined by the 
manufacturer. In this total, credit in excess 

of 30% of the total relieving capacity shall A07 
not be allowed for the power-actuated 
pressure-relieving valves actually installed. 
Any or all of the spring-loaded safety valves 
may be set above the maximum allowable 
working pressure of the parts to which they 
are connected, but the set pressures shall 
be such that when all these valves (together 
with the power-actuated pressure-relieving 
valves) are in operation the pressure will not 
rise more than 20% above the maximum 
allowable working pressure of any part 
of the boiler, except for the steam piping 
between the boiler and the prime mover. 

c) When stop valves are installed in the water- 
steam flow path between any two sections 
of a forced-flow steam generator with no 
fixed steamline and waterline: 

1) The power-actuated pressure-reliev- 
ing valve shall also receive a control 
impulse to open when the maximum 
allowable working pressure of the 
component, having the lowest pres- 
sure level upstream to the stop valve, 
is exceeded. 

2) The spring-loaded safety valve shall 
be located to provide overpressure 
protection for the component having 
the lowest working pressure. 

3) A reliable pressure-recording device 
shall always be in service and records 
kept to provide evidence of conformity 
to the above requirements. 



29 



NATIDNAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



2.9.3 



SUPERHEATERS 



a) Every attached superheater shall have one 
or more safety valves. The location shall 
be suitable for the service intended and 
shall provide the overpressure protection 
required. The pressure drop upstream of 
each safety valve shall be considered in 
determining the set pressure and relieving 
capacity of that valve. If the superheater 
outlet header has a full, free steam passage 
from end to end and is so constructed that 
steam is supplied to it at practically equal 
intervals throughout its length so that there 
is a uniform flow of steam through the su- 
perheater tubes and the header, the safety 
valve or valves may be located anywhere 
in the length of header. 

b) The pressure-relieving capacity of the safety 
valve or valves on an attached superheater 
shall be included in determining the num- 
ber and size of the safety valves for the 
boiler provided there are no intervening 
valves between the superheater safety valve 
and the boiler and the discharge capacity 

A07 of the safety relief valve or valves, on the 
boiler, as distinct from the superheater, 
is at least 75% of the aggregate capacity 
required. 

c) Every independently fired superheater that 
may be shut off from the boiler and permit 
the superheater to become a fired pressure 
vessel shall have one or more safety valves 
having a discharge capacity equal to six 
pounds of steam per hr/sq. ft. (29 kg per hr 
per sq. m) of superheater surface measured 
on the side exposed to the hot gases. 

d) Every safety valve used on a superheater 
discharging superheated steam at a tem- 
perature over 450°F (230°C) shall have a 
casing, including the base, body, bonnet, 
and spindle constructed of steel, steel alloy, 
or equivalent heat-resistant material. The 
valve shall have a flanged inlet connection 
or a welding-end inlet connection. The seat 
and disk shall be constructed of suitable 
heat-erosive and corrosive-resistant mate- 
rial, and the spring fully exposed outside of 



the valve casing so that it is protected from 
contact with the escaping steam. 



2.9.4 



ECONOMIZERS 



An economizer that may not be isolated from 
a boiler does not require a safety relief valve. 
Economizers that may be isolated from a boiler 
or other heat transfer device, allowing the 
economizer to become a fired pressure vessel, 
shall have a minimum of one safety relief valve. 
Discharge capacity, rated in Ibs/hr (kg/hr), of the 
safety relief valve or valves shall be calculated 
from the maximum expected heat absorption 
rate in Btu/hr (Joules/hr) of the economizer, and 
will be determined from manufacturer data, 
divided by 1000. The safety relief valve shall 
be located as close as possible to the econo- 
mizer outlet. 



2.9.5 PRESSURE-REDUCING VALVES 

a) Where pressure-reducing valves are used, 
one or more safety or safety relief valves 
shall be installed on the low pressure side 
of the reducing valve in those installations 
where the piping or equipment on the low 
pressure side does not meet the require- 
ments for the steam supply piping. 

b) The safety or safety relief valves shall be 
located as close as possible to the pressure- 
reducing valve. 

c) Capacity of the safety or safety relief valves 
shall not be less than the total amount of 
steam that can pass from the high pres- 
sure side to the low pressure side and be 
such that the pressure rating of the lower 
pressure piping or equipment shall not be 
exceeded. 

d) The use of hand-controlled bypasses around 
reducing valves is permissible. The bypass 
around a reducing valve may not be greater 
in capacity than the reducing valve unless the 
piping or equipment is adequately protected 
by safety or safety relief valves or meets the 
requirements of the high pressure system. 



3D 



NATIONAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



A09 2.9.6 MOUNTING AND DISCHARGE 

REQUIREMENTS 

a) Every boiler shall have outlet connections 
for the safety or safety relief valve, or valves, 
independent of any other outside steam 
connection, the area of opening shall be at 
least equal to the aggregate areas of inlet 
connections of all of the attached safety 
or safety relief valves. An internal collect- 
ing pipe, splash plate, or pan should be 
used, provided the total area for inlet of 
steam thereto is not less than twice the 
aggregate areas of the inlet connections of 
the attached safety or safety relief valves. 
The holes in such collecting pipes shall 
be at least 1/4 in. (6 mm) in diameter, and 
the least dimension in any other form of 
opening for inlet of steam shall be 1/4 in. 
(6 mm). If safety or safety relief valves are 
attached to a separate steam drum or dome, 
the opening between the boiler proper and 
the steam drum or dome shall be not less 
than 10 times the total area of the safety 
valve inlet. 

b) Every safety or safety relief valve shall be 
connected so as to stand in an upright posi- 
tion with spindle vertical. 

c) The opening or connection between the 
boiler and the safety or safety relief valve 
shall have at least the area of the valve 
inlet. No valve of any description should 
be placed between the safety or safety 
relief valves and the boiler, nor on the dis- 
charge pipe between the safety or safety 
relief valves and the atmosphere. When a 
discharge pipe is used, the cross-sectional 
area shall not be less than the full area of 
the valve outlet or of the total of the areas 
of the valve outlets, discharging thereinto 
and shall be as short and straight as pos- 
sible and arranged to avoid undue stresses 
on the valve or valves. 

d) When two or more safety valves are used 
on a boiler, they should be mounted either 
separately or as twin valves made by plac- 



ing individual valves on Y-bases, or duplex 
valves having two valves in the same body 
casing. Twin valves made by placing indi- 
vidual valves on Y-bases or duplex valves 
having two valves in the same body shall 
be of equal size. 

e) When two valves of different sizes are 
mounted singly, the relieving capacity of 
the smaller valve shall not be less than 50% 
of that of the larger valve. 

f) When a boiler is fitted with two or more 
safety relief valves on one connection, this 
connection to the boiler shall have a cross- 
sectional area not less than the combined 
areas of inlet connections of all the safety 
relief valves with which it connects. 

g) All safety or safety relief valves shall be 
piped to a safe point of discharge so located 
or piped as to be carried clear from running 
boards or platforms. Ample provision for 
gravity drain shall be made in the discharge 
pipe at or near each safety or safety relief 
valve, and where water or condensation 
may collect. Each valve shall have an open 
gravity drain through the casing below the 
level of the valve seat. For iron- and steel- 
bodied valves exceeding NPS 2 (DN 50), 
the drain hole shall be tapped not less than 
NPS 3/8 (DN 10). 

h) Discharge piping from safety relief valves 
on high temperature water boilers shall 
have adequate provisions for water drain- 
age as well as steam venting. 

i) If a muffler is used on a safety or safety relief 
valve, it shall have sufficient outlet area 
to prevent back pressure from interfering 
with the proper operation and discharge 
capacity of the valve. The muffler plates or 
other devices shall be so constructed as to 
avoid a possibility of restriction of the steam 
passages due to deposits. Mufflers shall not 
be used on high temperature water boiler 
safety relief valves. 



3 1 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



2.10 TESTING AND ACCEPTANCE 



2.10.1 GENERAL 



shipped connected to the boiler as a unit, shall 
be hydrostatically tested with the boiler and 
witnessed by an Inspector. 



a) Care shall be exercised during installation 
to prevent loose weld material, welding 
rods, small tools, and miscellaneous scrap 
metal from getting into the boiler. Where 
possible, an inspection of the interior of the 
boiler and its appurtenances shall be made 
for the presence of foreign debris prior to 
making the final closure. 

A07 b) Safe operation should be verified by a per- 
son familiar with boiler system operations 
for all boilers and connected appurtenances 
and all pressure piping connecting them to 
the appurtenances and all piping up to and 
including the first stop valve, or the second 
stop valve when two are required. 

c) The wall thickness of all pipe connections 
shall comply with the requirements of the 
code of construction for the boiler. 

d) All threaded pipe connections shall engage 
at least five full threads of the pipe or fit- 
ting. 

e) In bolted connections, the bolts, studs, and 
nuts shall be marked as required by the 
original Code of Construction and be fully 
engaged (e.g., the end of the bolt or stud 
shall protrude through the nut). 

f) Washers shall only be used when speci- 
fied by the manufacturer of the part being 
installed. 



2.10.2 



PRESSURE TEST 



Prior to initial operation, the completed boiler, 
including pressure piping, water columns, 
superheaters, economizers, stop valves, etc., 
shall be pressure tested in accordance with 
the original code of construction. Any pres- 
sure piping and fittings such as water columns, 
blowoff valves, feedwater regulators, superheat- 
ers, economizers, stop valves, etc., which are 



2.10.3 NONDESTRUCTIVE 

EXAMINATION 

Boiler components and subcomponents shall 
be nondestructively examined as required by 
the governing Code of Construction. 



2.10.4 SYSTEM TESTING 

Prior to final acceptance, an operational test 
shall be performed on the complete installation. 
The test data shall be recorded and the data 
made available to the jurisdictional authori- 
ties as evidence that the installation complies 
with the provisions of the governing code(s) of 
construction. This operational test may be used 
as the final acceptance of the unit. 



2.10.5 



FINAL ACCEPTANCE 



A boiler may not be placed into service until its 
installation has been inspected and accepted by 
the appropriate jurisdictional authorities. 



2.10.6 BOILER INSTALLATION REPORT 

a) Upon completion, inspection, and accep- 
tance of the installation, the installer shall 
complete and certify the Boiler Installation 
Report 1-1. See 1.4.5.1. 

b) The Boiler Installation Report 1-1 shall be 
submitted as follows: 

1 ) one copy to the Owner; and 

2) one copy to the Jurisdiction, if re- 
quired. 



32 



NATIDNAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



3.3.4 



CLEARANCES 



3.4.2 



LADDERS AND RUNWAYS 



a) Heating boilers shall have a minimum 
distance of at least 36 in. (914 mm) be- 
tween the top of the heating boiler and 
any overhead structure and at least 36 in. 
(914 mm) between all sides of the heating 
boiler and adjacent walls, structures, or 
other equipment. Heating boilers having 

A07 manholes shall have at least 84 in. (2135 
mm) of clearance between the manhole 
opening and any wall, ceiling, piping, 
or other equipment that may prevent a 
person from entering the heating boiler. 
Alternative clearances in accordance with 
the manufacturer's recommendations are 
subject to acceptance by the Jurisdiction. 

b) Modular heating boilers that require indi- 
vidual units to be set side by side, front to 
back or by stacking shall provide clearances 
in accordance with the manufacturer's 
recommendations, subject to acceptance 
by the Jurisdiction. 

c) Heating boilers shall be located so that 
adequate space is provided for proper op- 
eration, maintenance, 3 and inspection of 
equipment and appurtenances. 



a) All walkways, runways, and platforms shall 
be: 

1 ) of metal construction; 

2) provided between or over the top of 
boilers that are more than 8 ft. (2.4 m) 
above the operating floor to afford ac- 
cessibility for normal operation, main- A07 
tenance, and inspection; 

3) constructed of safety treads, standard 
grating, or similar material and have a 
minimum width of 30 in. (760 mm); 

4) of bolted, welded, or riveted construc- 
tion; and 

5) equipped with handrails 42 in. (1070 
mm) high with an intermediate rail and 
4 in. (1 00 mm) toe board. 

b) Stairways that serve as a means of access 
to walkways, runways, or platforms shall 
not exceed an angle of 45 degrees from the 
horizontal and be equipped with handrails 
42 in. (1 070 mm) high with an intermediate 
rail. A09 



3.4 



3.4.1 



BOILER ROOM REQUIREMENTS 



EXIT 



Two means of exit shall be provided for boiler 
rooms exceeding 500 sq. ft. (46.5 sq. m) of floor 
area and containing one or more boilers having 
a combined fuel capacity of 1 ,000,000 Btu/hr 
(293 kW) or more (or equivalent electrical heat 
input). Each elevation shall be provided with 
A07 at least two means of exit, each to be remotely 
located from the other. A platform at the top of 
a single boiler is not considered an elevation. 



Maintenance -This includes the removal of tubes. 



c) Ladders that serve as a means of access to 
walkways, runways, or platforms shall: 

1 ) be of metal construction and not less 
than 18 in. (460 mm) wide; 

2) have rungs that extend through the 
side members and are permanently 
secured; 

3) have a clearance of not less than 30 
in. (760 mm) from the front of rungs to 
the nearest permanent object on the 
climbing side of the ladder; 

4) have a clearance of not less than 6-1 12 
in. (1 65 mm) from the back of rungs to 
the nearest permanent object; and 



37 



NATIONAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



5) have a clearance width of at least 1 5 in. 
(380 mm) from the center of the ladder 
on either side across the front of the 
ladder. 

d) There shall be at least two permanently 
A07 installed means of exit from walkways, 
runways, or platforms that exceed 6 ft. (1 .8 
m) in length. 



3.5 



3.5.1 



SOURCE REQUIREMENTS 



WATER 



a) A means to add water to or fill the boiler, 
while not under pressure, shall be provided. 
A valve or threaded plug may be used to 
shut off the fill connection when the boiler 
is in service. 

A08 b) Water fill connections shall be installed. 
A means shall be provided at or near the 
boiler to prevent backfeeding. Such means 
shall be rated for the boiler design pressure 
and temperature. 

c) Provision should also be made in every 
boiler room for a convenient water supply 
that can be used to flush out the boiler and 
to clean the boiler room floor. 



3.5.2 



FUEL 



Fuel systems, whether firing coal, oil, gas, or 
other substance, shall be installed in accor- 
dance with jurisdictional and environmental re- 
quirements, manufacturer's recommendations, 
and/or industry standards, as applicable. 



3.5.3 



ELECTRICAL 



a) All wiring for controls, heat generating ap- 
paratus, and other appurtenances necessary 
for the operation of the boiler or boilers 



shall be installed in accordance with the 
provisions of national or international 
standards and comply with the applicable 
local electrical codes. 

b) A manually operated remote shutdown 
switch or circuit breaker shall be located A07 
just outside the boiler room door and 
marked for easy identification. Consider- 
ation should also be given to the type and 
location of the switch to safeguard against 
tampering. 

c) If the boiler room door is on the building 
exterior, the switch shall be located just 
inside the door. If there is more than one 
door to the boiler room, there shall be a 
switch located at each door of egress. A07 

1) For atmospheric-gas burners, and oil 
burners where a fan is on a common 
shaft with the oil pump, the complete 
burner and controls should be shut 
off. 

2) For power burners with detached auxil- 
iaries, only the fuel input supply to the 
firebox need be shut off. 

d) Controls and Heat Generating Apparatus 

1) Oil- and gas-fired and electrically 
heated boilers and water heaters shall 
be equipped with suitable primary 
(flame safeguard) safety controls, safety 
limit switches, and burners or electric 
elements as required by a nationally or 
internationally recognized standard. 

2) The symbol of the certifying orga- 
nization that has investigated such 
equipment as having complied with a 
nationally recognized standard shall 
be affixed to the equipment and shall 
be considered as evidence that the unit 
was manufactured in accordance with 
that standard. 



38 



NATIONAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



c) Potable Water Heaters 

1) Water supply shall be introduced into 
a water heater through an independent 
water supply connection. Feedwater 
shall not be introduced through open- 
ings or connections provided for clean- 
ing, safety relief valves, drain, pressure 
gage, or temperature gage. 

2) If the water supply pressure to a water 
heater exceeds 75% of the set pressure 
of the safety relief valve, a pressure 
reducing valve is required. 



3.7.5 STOP VALVES 



3.7.5.1 STEAM HEATING, HOT-WATER 
HEATING, AND HOT- WATER 
SUPPLY BOILERS 

A09 a) For Single Steam Heating Boilers 

When a stop valve is used in the supply 
pipe connection of a single steam boiler, 
there shall be one installed in the return 
pipe connection. 

A09 b) For Single Hot Water Heating & Hot Water 
Supply Boilers 

1) Stop valves shall be located at an ac- 
cessible point in the supply and return 
pipe connections as near the boiler as is 
convenient and practicable, of a single 
hot water boiler installation to permit 
draining the boiler without emptying 
the system. 

2) When the boiler is located above the 
system and can be drained without 
draining the system stop valves required 
in paragraph 3.7.5.1 b) 1 ) may be elimi- 
nated. 



boilers connected to a common system. 
See Figures 3.7.5 a), 3.7.5 b), and 3.7.5 c). 

d) Types of Stop Valve(s) 

1 ) All valves or cocks shall conform with 
the applicable portions of an accept- 
able code of construction and may be 
ferrous or nonferrous. 

2) The minimum pressure rating of all 
valves or cocks shall be at least equal 
to the pressure stamped upon the boiler, 
and the temperature rating of such 
valves or cocks, including all internal 
components, shall be not less than 
250°F(121°C). 

3) Valves or cocks shall be flanged, thread- 
ed or have ends suitable for welding or 
brazing. 

4) All valves or cocks with stems or 
spindles shall have adjustable pressure- 
type packing glands and, in addition, 
all plug-type cocks shall be equipped 
with a guard or gland. The plug or other 
operating mechanism shall be distinctly 
marked in line with the passage to in- 
dicate whether it is opened or closed. 

5) All valves or cocks shall have tight clo- 
sure when under boiler hydrostatic test 
pressure. 



A09 



3.7.5.2 



POTABLE WATER HEATERS 



A07 



Stop valves shall be installed in the supply 
and discharge pipe connections of a water 
heater installation to permit draining the water 
heater without emptying the system. See Figure 
3.7.5(d). 



3.7.6 



RETURN PIPE CONNECTIONS 



A09 c) For Multiple Boiler Installations 

A stop valve shall be used in each supply- 
and-return pipe connection of two or more 



The return pipe connections of each boiler 
supplying a gravity return steam heating 
system shall be so arranged as to form a loop 
substantially as shown in Figure 3.7.5-b 



4 i 



NATIONAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



so that the water in each boiler cannot be 
forced out below the safe water level. 

b) For hand-fired boilers with a normal grate 
line, the recommended pipe sizes detailed 
as "A" in Figures 3.7.5-a and 3.7.5-b are 
NPS 1-1/2 (DN 40) for 4 sq. ft (0.37 sq. m) 
or less firebox area at the normal grate line, 
NPS 2-1/2 (DN 65) for areas more than 4 
sq. ft (0.37 sq. m) up to 1 4.9 sq. ft (1 .38 sq. 
m), and NPS 4 (DN 1 00) for 1 5 sq. ft (1 .39 
sq. m) or more. 

c) For automatically-fired boilers that do not 
have a normal grate line, the recommended 
pipe sizes detailed as "A" in Figures 3.7.5- 
a and 3.7.5-b are NPS 1-1/2 (DN 40) for 



boilers with minimum safety valve relieving 
capacity 250 Ib/hr (1 1 3 kg/hr) or less, NPS 
2-1/2 (DN 65) for boilers with minimum 
safety valve relieving capacity from 251 
Ib/hr (114 kg/hr) to 2000 Ib/hr (907 kg/hr), 
inclusive, and NPS 4 (DN 100) for boil- 
ers with more than 2000 Ib/hr (907 kg/hr) 
minimum safety valve relieving capacity. 

d) Provision shall be made for cleaning the 
interior of the return piping at or close to the 
boiler. Washout openings should be used 
for return pipe connections and the wash- 
out plug placed in a tee or a cross so that 
the plug is directly opposite and as close 
as possible to the opening in the boiler. 



FIGURE 3.7.5-a 
Steam boilers in battery 



pumped return — acceptable piping installation 



Steam main 



Heating 

supply 




From receiver lank 



General Note: 

Return connections shown for a multiple boiler installation may not always 

ensure that the system will operate properly. In order to maintain proper water levels in multiple 

boiler installations, it may he necessary to install supplementary controls or suitable devices. 

Note: 

(1) Recommended for 1 in. (25 mm) and larger safety valve discharge. 



42 



NATIONAL BDARD INSPECTION CODE • PART 1 — INSTALLATION 



A07 



FIGURE 3.7.5-d 

Storage Potable Water Heaters in Battery - Acceptable Piping installation 



rt—fy — w * — i- 



^<- 



-Ja — *-k 




i>- 



To Open Drain 



Cold Water Supply 



4 — &th 



$? c y, 



Water Heater with Top 



-i i/i-^*- 




Drain Valve with 
Suitable Drain 



Point of Use 



A 




l/ D C ^ 



Drain Valve 



(1) 



system may be gravity or pump actuated. 



A07 



FIGURE 3.7.5-e 

Flow Through Potable Water Heater Without Provision for Piping Expansion - Acceptable 

Piping Installation 



-ut- 



-* ^ 



Flow switch on 



& 




o S^ 




-Drain valve 



-Optical 
reci 

line 



45 



NATIPNAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



3.7.7 BOTTOM BLOWOFF AND 

DRAIN VALVES 



rating of such valves and cocks shall not 
be less than 250°F (121°C). 



3.7.7.1 STEAM HEATING, HOT-WATER 
HEATING, AND HOT-WATER 
SUPPLY BOILERS 

a) Bottom Blowoffs 

1) Each steam boiler shall have a bottom 
blowoff connection fitted with a valve 
or cock connected to the lowest water 
space practicable with a minimum 
size as shown in Table 3.7.7.1. The 
discharge piping shall be full size to 
the point of discharge. 

2) Boilers having a capacity of 25 gallons 
(95 I) or less are exempt from the above 
requirements, except that they shall 
have a NPS 3/4 (DN 20) minimum drain 
valve. 

b) Drains 

1) Each steam or hot-water boiler shall 
have one or more drain connections, 
fitted with valves or cocks connecting 
to the lowest water containing spaces. 
All parts of the boiler must be capable 
of being drained (the boiler design will 
dictate the number and size of drains). 
The minimum size of the drain piping, 
valves, and cocks shall be NPS 3/4 (DN 
20). The discharge piping shall be full 
size to the point of discharge. 

2) When the blowoff connection is located 
at the lowest water containing space, 
a separate drain connection is not re- 
quired. 

c) Minimum Pressure Rating 

The minimum pressure rating of valves 
and cocks used for blowoff or drain pur- 
poses shall beat least equal to the pressure 
stamped on the boiler but in no case less 
than 30 psig (200 kPa). The temperature 



TABLE 3.7.7.1 

Size of bottom blowoff piping, valves, and 

cocks 



Minimum Required 
Safety Valve Capacity, lbs. 
of steam/hr (Note 1) 


Blowoff Piping, 
Valve, and Cock 
Sizes, in. (mm)(min.) 


up to 500 

(up to 227 kg) 


3/4 
(19) 


501 to 1,250 

(over 227 kg to 567 kg) 


1 
(25) 


1,251 to 2,500 

(over 567 kg to 1134 kg) 


1-1/4 

(32) 


2,501 to 6,000 

(over 1134 kg to 2722 kg) 


1-1/2 
(38) 


6,001 and larger 
(over 2722 kg) 


2 

(50) 


Note 1 : To determine the discharge capacity of 
the safety relief valves in terms of total energy 
absorbed, use 1 lb steam per hour per 1 000 Btu (1 
kg steam per hour per 2326 kj). 



3.7.7.2 POTABLE WATER HEATERS 

Drain Valve 

a) Each water heater shall have a bottom 
drain pipe connection fitted with a valve 
or cock connected with the lowest water 
space practicable. The minimum size bot- 
tom valve shall be NPS 3/4 (DN 20). 

b) Any discharge piping connected to the bot- 
tom drain connection shall be full size to 

the point of discharge. See Figures 3.7. 5-d A07 
and 3.7.5-e. 



46 



NATIONAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



3.7.8 



3.7.8.1 



MODULAR STEAM HEATING 
AND HOT-WATER HEATING 
BOILERS 



INDIVIDUAL MODULES 



a) The individual modules shall comply with 
all the requirements of the code of construc- 
tion and this paragraph. The individual mod- 
ules shall be limited to a maximum input of 

A07 400,000 Btu/hr (117 kW/hr), gas 3 gal./hr 
(1 1 .4 l/hr), oil or 1 1 7 kW (electricity). 

b) Each module of a modular steam heating 
boiler shall be equipped with: 

1) Safety valve, see 3.9.2. 

2) Blowoff valve, see 3.7.7.1 (a). 

3) Drain valve, see 3.7.7.1(b). 

c) Each module of a modular hot-water heat- 
ing boiler shall be equipped with: 

1) Safety relief valve, see 3.9.3. 

2) Drain valve, see 3.7.7.1(b). 



3.7.8.2 ASSEMBLED MODULAR 
BOILERS 

a) The individual modules shall be manifolded 
together at the job-site without any inter- 
vening valves. 

b) The assembled modular steam heating 
boiler shall also be equipped with: 

1) Feedwater connection, see Figures 
3.7.5-a and 3.7.5-b. 

2) Return pipe connection, see Figures 
3.7.5-a and 3.7.5-b. 

c) The assembled modular hot water boiler 
shall also be equipped with: 



1) Makeup water connection, see Figure 
3.7.5-c. 

2) Provision for thermal expansion, see 
Figures 3.7.5-c and Table 3.7.9.1 -a. 

3) Stop valves, see Figure 3.7.5-c (treat- 
ing the assembled modular boiler as a 
single unit). 



3.7.9 PROVISIONS FOR THERMAL 

EXPANSION 



3.7.9.1 EXPANSION TANKS AND 

PIPING FOR STEAM HEATING, 
HOT-WATER HEATING AND 

HOT-WATER SUPPLY BOILERS A09 

a) Expansion Tanks for Hot-Water Heating, 
and Hot-Water Supply Boilers 
All hot-water heating systems incorporating 
hot-water tanks or fluid relief columns shall 
be so installed as to prevent freezing under 
normal operating conditions. 

1 ) Heating Systems With Open Expansion 
Tank 

An indoor overflow from the upper 
portion of the expansion tank shall be 
provided in addition to an open vent, 
the indoor overflow shall be carried 
within the building to a suitable plumb- 
ing fixture or drain. 

2) Closed Heating Systems 

An expansion tank shall be installed 
that will be consistent with the volume 
and capacity of the system. If the system 
is designed for a working pressure of 30 
psig (200 kPa) or less, the tank shall be 
suitably designed for a minimum hydro- 
static test pressure of 75 psig (520 kPa). 
Expansion tanks for systems designed to 
operate above 30 psig (200 kPa) shall 
be constructed in accordance with 
an acceptable code of construction. 
Provisions shall be made for draining 
the tank without emptying the system. 
Except for prepressurized tanks, the 



47 



NATIONAL. BOARD INSPECTION CODE • PART 1 



INSTALLATION 



A09 



minimum capacity of the closed-type 
expansion tank should be determined 
from Tables 3.7.9.1 -a and 3.7.9.1 -b or 
from the following formula where the 
necessary information is available: 

US Customary: 

V t = (0.0004 7T - 0.0466)V 
(P?P f )-(P/P) 



where, 





v ,= 


minimum volume of tanks, 
gallons 




V = 

s 


volume of system, not 
including tanks, gallons 




T = 


(t2-t1)°F 


A07 


t, = 


lower temperature 


A07 


t 2 = 


higher temperature 




P = 

a 


atmospheric pressure, psia 




P f = 


fill pressure, psia 




P = 




maximum operating 
pressure, psia 


A07 


Metric 






v,= 


(0.0007387- 0.0.3348)V s 



(P/PJ - (P/P 



where, 



V 



T = 



P = 

a 



minimum volume of tanks, 
liters 

volume of system, not 
including tanks, liters 
average operating 
temperature, °C 
atmospheric pressure, kPa 
fill pressure, kPa 
maximum operating 
pressure, kPa 



3) 



Hot-Water Supply Systems 
If a system is equipped with a check 
valve or pressure-reducing valve in 
the cold water inlet line, consideration 
should be given to the installation of an 
airtight expansion tank or other suitable 
air cushion. Otherwise, due to the ther- 
mal expansion of the water, the safety 
relief valve may lift periodically. If an 
expansion tank is provided, it shall be 



Table 3.7.9.1 -a 

Expansion Tank Capacities for Gravity Hot- 
Water Systems 



(Based on two-pipe system with average operating 

water temperature 1 70°F (77°C), using cast-iron 

column radiation with heat emission rate 

150 Btu/hr sq. ft. (473 W/sq. m) equivalent direct 

radiation.) 


Installed Equivalent 
Direct Radiation, sq. 
ft. (sq. m) (Note) 


No. 


Tank Capacity, 
gallon (1) 


up to 350 (33) 




1 8 (68) 


up to 450 (42) 




21 (80) 


up to 650 (60) 




24(91) 


up to 900 (84) 




30(114) 


up to 1,100 (102) 




35(132) 


up to 1,400 (130) 




40(151) 


up to 1,600 (149) 


2 


60 (228) 


up to 1,800 (167) 


2 


60 (228) 


up to 2,000 (186) 


2 


70 (264) 


up to 2,400 (223) 


2 


80 (302) 


Note: For systems with more than 2,400 sq. ft. 
(223 sq. m) of installed equivalent direct water 
radiation, the required capacity of the cushion 
tank shall be increased on the basis of 1 gallon 
(3.81 1) tank capacity/33 sq. ft. (3 sq. m) of 
additional equivalent direct radiation. 



constructed in accordance with an ac- 
ceptable code of construction. Except 
for prepressurized tanks, which should 
be installed on the cold water side, 
provisions shall be made for draining 
the tank without emptying the system. 
See Figures 3.7.5-d and 3.7.5-e for a 
typical acceptable installation. 

b) Piping for Steam Heating, Hot-water Heat- 
ing, and Hot-water Supply Boilers 
Provisions shall be made for the expansion 
and contraction of steam and hot water 
mains connected to boiler(s) so there will be 
no undue strain transmitted to the boiler(s). 
See Figures 3.7.5-a, 3.7.5-b, and 3.7.5-c for 
typical schematic arrangements of piping 
incorporating strain absorbing joints for 
steam and hot-water heating boilers. 



4B 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



Table 3.7.9.1 -b 

Expansion Tank Capacities for Forced Hot- 
Water Systems (Note) 



Table 3.7.9.2 

Expansion Tank Capacities for a Potable 

Water Heater (Note) 



A09 



(Based on average operating water temperature 
195°F [91 °C], fill pressure 12 psig [83 kPa], and 
maximum operating pressure 29 psig [200 kPa]) 


Tank Capacities, gal (I) 


System 
Volume, 

gal (I) 


Prepressurized 
Diaphragm 

type 


Nonpressurized 
type 


100(380) 


9(34) 


18(57) 


200 (760) 


1 7 (64) 


30(114) 


300(1140) 


25 (95) 


45 (1 70) 


400(1514) 


33(125) 


60 (227) 


500(1890) 


42(159) 


75 (284) 


1,000(3790) 


83 (315) 


150(568) 


2,000 (7570) 


165 (625) 


300(1136) 


Note: System volume includes volume of water in 
boiler, radiation, and piping, not including the ex- 
pansion tank. Expansion tank capacities are based 
on an acceptance factor of 0.4027 for prepressur- 
ized types and 0.222 for nonpressurized types. 

For other cases or metric calculations see Chapter 
1 2 of the 1 996 HVAC Systems and Equipment 
Volume of the ASHRAE Handbook. 



3.7.9.2 EXPANSION TANKS AND 

PIPING FOR POTABLE WATER 
HEATERS 

a) Expansion Tanks 

If a system is equipped with a check valve 
or pressure-reducing valve in the cold water 
inlet line, consideration should be given to 
the installation of an airtight expansion tank 
or other suitable air cushion. Otherwise, 
due to the thermal expansion of the water, 
the safety relief valve may lift periodically. 
If an expansion tank is provided, it shall be 
constructed in accordance with an accept- 
able code of construction. The minimum 
capacity of the expansion tank may be 
A09 determined from Table 3.7.9.2. (See Figures 
3.7.5-d and 3.7.5-e for a typical acceptable 



Tank Capacities, gal. (I) 


System 
Volume, 
gal. (I) 


Prepressurized 

Diaphragm 

type 


Nonpressurized 
type 


50(190) 


1 (4) 


3(11) 


100(380) 


2(8) 


6(23) 


200 (760) 


3(11) 


12 (45) 


300(1140) 


4(15) 


18(68) 


400(1514) 


5(19) 


24(91) 


500(1890) 


6(23) 


30(114) 


1,000(3790) 


12 (45) 


60 (227) 


2,000 (7570) 


24(91) 


120(454) 


Note: Capacities in this table are given as a guide 
to reduce or eliminate relief valve weeping under 
conditions of partial water system demands or oc- 
casional water draw during recovery. 

System volume includes water heater capacity plus 
all piping capacity for a recirculation system or 
potable water heater capacity only for a nonrecir- 
culation system. 

The capacities are based upon a water temperature 
rise from 40°F to 1 80°F (4°C to 82°C), 60 psig 
(414 kPa) fill pressure, maximum operating pres- 
sure of 1 25 psig (862 kPa) 20% water recovery, 
and an acceptance factor of 0.465 for prepressur- 
ized types, and 0.091 56 for nonpressurized types. 
For other cases or metric calculations see Chapter 
1 2 of the 1 996 HVAC Systems and Equipment 
Volume of the ASHRAE Handbook. 



A09 



installation.) Except for pre-pressurized 
diaphragm-type tanks, which should be 
installed on the cold water side, provisions 
shall be made for draining the tank without 
emptying the system. 

b) Piping 

Provisions shall be made for the expansion 
and contraction of hot water mains con- 
nected to potable water heater(s) so that A07 
there will be no undue stess transmitted 
to the potable water heater(s). (See Figures AQ9 
3.7.5-d and 3.7.5-e for typical schematic 
arrangements of piping incorporating strain 
absorbing joints). 



49 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



3.8 



3.8.1 



INSTRUMENTS, FITTINGS, AND 
CONTROLS 



STEAM HEATING BOILERS 



3.8.1.1 STEAM GAGES 

a) Each steam boiler shall have a steam gage 
or a compound steam gage connected to its 
steam space or to its water column or to its 
steam connection. The gage or connection 
shall contain a siphon or equivalent device 
that will develop and maintain a water 
seal that will prevent steam from entering 
the gage tube. The connection shall be so 
arranged that the gage cannot be shut off 
from the boiler except by a cock placed in 
the pipe at the gage and provided with a 
tee-handle or lever-handle arranged to be 
parallel to the pipe in which it is located 
when the cock is open. The connections 
to the boiler shall be not less than NPS 1/4 
(DN 8). Where steel or wrought iron pipe 
or tubing is used, the connection and ex- 
ternal siphon shall be not less than NPS 1/2 
(DN 1 5). The minimum size of a siphon, if 
used, shall be NPS 1/4 (DN 8). Ferrous and 
nonferrous tubing having inside diameters 
at least equal to that of standard pipe sizes 
listed above may be substituted for pipe. 

b) The scale on the dial of a steam boiler gage 
shall be graduated to not less than 29 psig 
(200 kPa) nor more than 58 psig (400 kPa). 
The travel of the pointer from psig (0 kPa) 
to 29 psig (200 kPa) pressure shall be at 
least 3 in. (76 mm). 



3.8.1 .2 WATER GAGE GLASSES 

a) Each steam boiler shall have one or more 
water gage glasses attached to the water 
column or boiler by means of valved fittings 
not less than NPS 1/2 (DN 15), with the 
lower fitting provided with a drain valve of 
a type having an unrestricted drain opening 



not less than NPS 1/4 (DN 8) to facilitate 
cleaning. Gage glass replacement shall be 
possible under pressure. Water glass fittings 
may be attached directly to a boiler. Boilers 
having an internal vertical height of less 
than 10 in. (254 mm) should be equipped 
with a water level indicator of the glass 
bulls-eye type provided the indicator is of 
sufficient size to show the water at both 
normal operating and low-water cutoff 
levels. 

b) The lowest visible part of the water gage 
glass shall be at least 1 in. (25 mm) above 
the lowest permissible water level recom- 
mended by the boiler manufacturer. With 
the boiler operating at this lowest permis- 
sible water level, there shall be no danger 
of overheating any part of the boiler. 

c) In electric boilers of the submerged elec- 
trode type, the water gage glass shall be so 
located to indicate the water levels both 
at startup and under maximum steam load 
conditions as established by the manufac- 
turer. 

d) In electric boilers of the resistance element 
type, the lowest visible part of the water 
gage shall be located at least 1 in. (25 mm) 
above the lowest permissible water level 
specified by the manufacturer. Each electric 
boiler of this type shall also be equipped 
with an automatic low-water cutoff on 
each boiler pressure vessel so located as 
to automatically cut off the power supply 
to the heating elements before the surface 
of the water falls below the visible part of 
the glass. 

e) Tubular water glasses on electric boilers 
having a normal water content not exceed- 
ing 1 00 gal. (380 I) shall be equipped with 
a protective shield. 

Note: Transparent material other than glass 
may be used for the water gage provided 
that the material will remain transparent 
and has proved suitable for the pressure, 



5D 



NATIONAL BOARD INSPECTION CDDE • PART 1 



INSTALLATION 



temperature, and corrosive conditions ex- 
pected in service. 



3.8.1 .3 WATER COLUMN AND WATER 
LEVEL CONTROL PIPES 

a) The minimum size of ferrous or nonferrous 
pipes connecting a water column to a steam 
boiler shall be NPS 1 (DN 25). No outlet 
connections, except for damper regulator, 
feedwater regulator, steam gages, or ap- 
paratus that does not permit the escape of 
any steam or water except for manually 
operated blowdown, shall be attached to 
a water column or the piping connecting a 
water column to a boiler (see 3.7.4[a]) for 
introduction of feedwater into a boiler). If 
the water column, gage glass, low-water 
fuel cutoff, or other water level control 
device is connected to the boiler by pipe 
and fittings, no shutoff valves of any type 
shall be placed in such pipe and a cross or 
equivalent fitting to which a drain valve and 
piping may be attached shall be placed in 
the water piping connection at every right 
angle turn to facilitate cleaning. The water 
column drain pipe and valve shall be not 
less than NPS 3/4 (DN 20). 

b) The steam connections to the water column 
of a horizontal firetube wrought boiler shall 
betaken from the top of the shell or the up- 
per part of the head, and the water connec- 
tion shall be taken from a point not above 
the center line of the shell. For a cast-iron 
boiler, the steam connection to the water 
column shall be taken from the top of an 
end section or the top of the steam header, 
and the water connection shall be made on 
an end section not less than 6 in. (1 52mm) 
below the bottom connection to the water 
gage glass. 



3.8.1.4 PRESSURE CONTROL 

Each automatically fired steam boiler shall be 
protected from overpressure by two pressure- 
operated controls. 



a) Each individual steam boiler or each sys- A08 
tern of commonly connected steam boilers 
shall have a control that will cut off the fuel 
supply when the steam pressure reaches an 
operating limit, which shall be less than the 
maximum allowable pressure. 

b) Each individual automatically fired steam 
boiler shall have a safety limit control, 
with a manual reset, that will cut off the A08 
fuel supply to prevent steam pressure from 
exceeding the 1 5 psig (1 00 kPa) maximum 
allowable working pressure of the boiler. 
Each control shall be constructed to pre- 
vent a pressure setting above 1 5 psig (1 00 
kPa). 

c) Shutoff valves of any type shall not be 
placed in the steam pressure connection 
between the boiler and the controls de- 
scribed in (a) and (b) above. These controls 
shall be protected with a siphon or equiva- 
lent means of maintaining a water seal 
that will prevent steam from entering the 
control. The connections to the boiler shall 
not be less than NPS 1/4 (DN 8), but where 
steel or wrought iron pipe or tubing is used, 
they shall not be less than NPS 1/2 (DN 15). 
The minimum size of an external siphon 
shall be NPS 1/4 (DN 8) or 3/8 in. (1 mm) 
outside diameter nonferrous tubing. For 
manifold connections, the minimum size 
shall be as specified in the original code 
of construction. 



3.8.1.5 AUTOMATIC LOW-WATER FUEL 
CUTOFF AND/OR WATER 
FEEDING DEVICE 

a) Each automatically-fired steam- or vapor- 
system boiler shall have an automatic 
low-water fuel cutoff so located as to auto- 
matically cut off the fuel supply when the 
surface of the water falls to the lowest vis- 
ible part of the water gage glass. If a water 
feeding device is installed, it shall be so 
constructed that the water inlet valve can- 
not feed water into the boiler through the 
float chamber and so located as to supply 
requisite feedwater. 



5 1 



NATIDNAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



b) Such a fuel cutoff or water feeding device 
may be attached directly to a boiler. A fuel 
cutoff or water feeding device may also be 
installed in the tapped openings available 
for attaching a water glass directly to a 
boiler, provided the connections are made 
to the boiler with nonferrous tees or Y's 
not less than NPS 1/2 (DN 15) between 
the boiler and water glass so that the water 
glass is attached directly and as close as 
possible to the boiler; the run of the tee or 
Y shall take the water glass fittings, and the 
side outlet or branch of the tee or Y shall 
take the fuel cutoff or water feeding device. 
The ends of all nipples shall be reamed to 
full-size diameter. 

A08 c) In addition to the requirements in a) and b) 
above, a secondary low water fuel cutoff 
with manual reset shall be provided on 

A09 eacn automatically fired steam or vapor- 
system boiler. 

A08 d) Fuel cutoffs and water feeding devices 
embodying a separate chamber shall have 
a vertical drain pipe and a blowoff valve 
not less than NPS 3/4 (DN 20), located at 
the lowest point in the water equalizing 
pipe connections so that the chamber and 
the equalizing pipe can be flushed and the 
device tested. 



3.8.1.7 INSTRUMENTS, FITTINGS, AND 
CONTROLS MOUNTED INSIDE 
BOILER JACKETS 

Any or all instruments, fittings, and controls 
required by these rules may be installed inside 
of boiler jackets provided the water gage and 
pressure gage on a steam boiler are visible 
through an opening or openings at all times. 



3.8.2 HOT-WATER HEATING OR HOT- 

WATER SUPPLY BOILERS 



3.8.2.1 PRESSURE OR ALTITUDE GAGES 

a) Each hot-water heating or hot-water supply 
boiler shall have a pressure or altitude gage 
connected to it or to its flow connection 
in such a manner that it cannot be shut off 
from the boiler except by a cock with tee 
or lever handle, placed on the pipe near 
the gage. The handle of the cock shall be 
parallel to the pipe in which it is located 
when the cock is open. 

b) The scale on the dial of the pressure or alti- 
tude gage shall be graduated approximately 
to not less than 1-1/2 nor more than 3-1/2 
times the pressure at which the safety relief 
valve is set. 



3.8.1.6 MODULAR STEAM HEATING 
BOILERS 

a) Each module of a modular steam boiler 
shall be equipped with: 

1) Steam gage, see 3.8.1 .1 . 

2) Water gage glass, see 3.8.1 .2. 

3) Pressure control, see 3.8.1 .4(a). 

4) Low-water cutoff, see 3.8.1 .5. 

b) The assembled modular steam heating 
boiler shall also be equipped with a pres- 
sure control. See 3.8.1 .4(b). 



Piping or tubing for pressure or altitude 
gage connections shall be of nonferrous 
metal when smaller than NPS 1 (DN 25). 



3.8.2.2 



THERMOMETERS 



Each hot-water heating or hot-water supply 
boiler shall have a thermometer so located and 
connected that it shall be easily readable. The 
thermometer shall be so located that it shall at 
all times indicate the temperature of the water 
in the boiler at or near the outlet. 



52 



NATIONAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



3.8.2.3 TEMPERATURE CONTROL 

Each automatically fired hot-water heating or 
hot-water supply boi ler shal I be protected from 
over-temperature by two temperature-operated 
controls. 



A08a) 



A09 



A08 D ) 



A09 



Each individual hot-water heating or hot- 
water supply boiler or each system of 
commonly connected boilers shall have a 
control that will cut off the fuel supply when 
the water temperature reaches an operating 
limit, which shall be less than the maximum 
allowable temperature. 

In addition to a) above, each individual 
automatically fired hot-water heating or 
hot-water supply boiler shall have a safety 
limit control with manual reset that will 
cut off the fuel supply to prevent the water 
temperature from exceeding the maximum 
allowable temperature at the boiler out- 
let. 



3.8.2.4 



LOW-WATER FUEL CUTOFF 



a) Each automatically fired hot-water boiler 
shall have an automatic low-water fuel 
cutoff with manual reset. The low-water 

A08 fuel cutoff shall be designed for hot-water 

A09 service, and it shall be so located as to 

automatically cut off the fuel supply when 

the surface of the water falls to the level 

established in (b) below. 

b) As there is no normal waterlineto be main- 
tained in a hot-water boiler, any location of 
the low-water fuel cutoff above the lowest 
safe permissible water level established by 
the boiler manufacturer is satisfactory. 

A09 c) In lieu of the requirements for low-water 
fuel cutoffs in paragraph a), boilers requir- 
ing forced circulation to prevent overheat- 
ing of the tubes, coils, or vessel, shall have 
an accepted flow, and/or temperature- 
sensing device to prevent burner operation 
at a flow rate inadequate to protect the 



boiler unit against overheating at all allow- A08 
able firing rates. This safety control(s) shall 
shut down the burner and prevent restarting 
until an adequate flow is restored and shall 
be independent of all other controls. 

d) A means shall be provided for testing the 
operation of the external low-water fuel 
cutoff without resorting to draining the 
entire system. Such means shall not render 
the device inoperable except as follows. If 
the means temporarily isolates the device 
from the boiler during this testing, it shall 
automatically return to its normal position. 
The connection may be so arranged that the 
device cannot be shut off from the boiler 
except by a cock placed at the device and 
provided with a tee or lever-handle ar- 
ranged to be parallel to the pipe in which 
it is located when the cock is open. 



3.8.2.5 MODULAR HOT-WATER 
HEATING BOILERS 

a) Each module of a modular hot-water heat- 
ing boiler shall be equipped with: 

1) Pressure/altitude gage, see 3.8.2.1 . 

2) Thermometer, see 3.8.2.2. 

3) Temperature control, see 3.8.2.3(a). 

b) The assembled modular hot-water heating 
boiler shall be equipped with: 

1) Temperature control, see 3.8.2.3(b). 

2) Low-water fuel cutoff, see 3.8.2.4. 



3.8.2.6 INSTRUMENTS, FITTINGS, AND 
CONTROLS MOUNTED INSIDE 
BOILER JACKETS 

Any or all instruments, fittings, and controls 
required by these rules may be installed inside 



53 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



of boi ler jackets provided the thermometer and 
pressure gage are visible through an opening 
or openings at all times. 



3.8.3 POTABLE WATER HEATERS 



3.8.3.1 TEMPERATURE CONTROLS 

Each individual automatically fired water 
heater, in addition to the operating control 
used for normal water heater operation, shall 
have a separate high limit temperature actuated 
combustion control that will automatically cut 
off the fuel supply. The temperature range of the 
high limit temperature actuated control shall 
not allow a setting over 21 0°F (99°C). 

a) On gas-fired water heaters, the high limit 
temperature control when actuated shall 
shut off the fuel supply with a shutoff 
means other than the operating control 
valve. Separate valves may have a common 
body. 

b) On electrically heated water heaters, the 
high limit temperature control when actu- 
ated shall cut off all power to the operating 
controls. 

c) On oil-fired water heaters, the high limit 
temperature control when actuated shall 
cut off all current flow to the burner mecha- 
nism. 



3.9 PRESSURE-RELIEVING VALVES 



3.9.1 SAFETY VALVE REQUIREMENTS 

— GENERAL 



A07 



The following general requirements pertain to 
installing, mounting, and connecting safety 
valves on boilers. 



3.9.1.1 MOUNTING SAFETY AND 
SAFETY RELIEF VALVES FOR 
STEAM HEATING, HOT-WATER 
HEATING, AND HOT-WATER 
SUPPLY BOILERS 



3.9.1.1.1 PERMISSIBLE MOUNTING 

Safety valves and safety relief valves shall be 
located at the top side 5 of the boiler. They shall 
be connected directly to a tapped or flanged 
opening in the boiler, to a fitting connected to 
the boiler by a short nipple, to a Y-base, or to 
a valveless header connecting steam or water 
outlets on the same boiler. Coil- or header-type 
boilers shall have the safety valve or safety relief 
valve located on the steam or hot water outlet 
end. Safety valves and safety relief valves shall 
be installed with their spindles vertical. The 
opening or connection between the boiler and 
any safety valve or safety relief valve shall have 
at least the area of the valve inlet. 



d) On indirect water heating systems, the high 
limit temperature control when activated 
shall cut off the source of heat. 



3.9.1.1.2 REQUIREMENTS FOR 

COMMON CONNECTIONS FOR 

TWO OR MORE VALVES 



3.8.3.2 



THERMOMETER 



Each installed water heater shall have a ther- 
mometer so located and connected that it shal I 
be easily readable. The thermometer shall be 
so located that it shall at all times indicate the 
temperature of the water in the water heater at 
or near the outlet. 



a) When a boiler is fitted with two or more 
safety valves on one connection, this con- 
nection shall have a cross-sectional area 
not less than the combined areas of inlet 
connections of all the safety valves with 
which it connects. 



5 Side — The top side of the boiler shall mean the highest 
practicable part of the boiler proper but in no case shall the 
safety valves be located below the normal operating level and 
in no case shall the safety relief valve be located below the low- 
est permissable water level. 



54 



NATIONAL BDARD INSPECTION CODE • PART 1 — INSTALLATION 



b) When a Y-base is used, the inlet area shall 
be not less than the combined outlet areas. 
When the size of the boiler requires a safety 
valve or safety relief valve larger than NPS 
4 (DN100), two or more valves having 
the required combined capacity shall be 
used. When two or more valves are used 
on a boiler, they may be single, directly 
attached, or mounted on a Y-base. 



3.9.1.2 THREADED CONNECTIONS 

A threaded connection may be used for attach- 
ing a valve. 



b) The discharge from safety or safety relief 
valves shall be so arranged that there will be 
no danger of scalding attendants. The safety 
or safety relief valve discharge shall be 
piped away from the boiler to a safe point A07 
of discharge, and there shall be provisions 
made for properly draining the piping. The 
size and arrangement of discharge piping 
shall be such that any pressure that may 
exist or develop will not reduce the reliev- 
ing capacity of the relieving devices below 
that required to protect the boiler. 



3.9.1 .6 TEMPERATURE AND PRESSURE 

SAFETY RELIEF VALVES 



A09 



3.9.1.3 PROHIBITED MOUNTINGS 

Safety and safety relief valves shall not be con- 
nected to an internal pipe in the boiler. 



3.9.1.4 USE OF SHUTOFF VALVES 
PROHIBITED 

No shutoff of any description shall be placed 
between the safety or safety relief valve and 
the boiler or on discharge pipes between such 
valves and the atmosphere. 



3.9.1 .5 SAFETY AND SAFETY RELIEF 
VALVE DISCHARGE PIPING 

a) A discharge pipe shall be used. Its internal 
cross-sectional area shall be not less than 
the full area of the valve outlet or of the total 
of the valve outlets discharging thereinto, 
and shall be as short and straight as pos- 
sible and so arranged as to avoid undue 
stress on the valve or valves. A union may 
be installed in the discharge piping close to 
the valve outlet. When an elbow is placed 
on a safety or a safety relief valve discharge 
pipe, it shall be located close to the valve 
outlet downstream of the union to minimize 
reaction moment stress. 



Hot-water heating or supply boilers limited to 
a water temperature of 2 1 0°F (99°C) may have 
one or more National Board capacity certified 
temperature and pressure safety relief valves 
installed. The requirements of 3.9.1 .1 through 
3.9.1 .5 shall be met, except as follows: 

a) A Y-type fitting shall not be used. 

b) If additional valves are used, they shall 
be temperature and pressure safety relief 
valves. 

c) When the temperature and pressure safety 
relief valve is mounted directly on the 
boiler with no more than 4 in. (100 mm) 
maximum interconnecting piping, the valve 
should be installed in the horizontal posi- 
tion with the outlet pointed down. 



3.9.2 SAFETY VALVE REQUIREMENTS 

FOR STEAM BOILERS 

a) Safety valves are to be manufactured in ac- 
cordance with a national or international 
standard. 

b) Each steam boiler shall have one or more 
National Board capacity certified safety 
valves of the spring pop type adjusted and 
sealed to discharge at a pressure not to 
exceed 15 psig (100 kPa). 



55 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



c) No safety valve for a steam boiler shall be 
smaller than NPS 1/2 (DN 15). No safety 
valve shall be larger than NPS 4 (DN 1 00). 
The inlet opening shall have an inside di- 
ameter equal to, or greater than, the seat 
diameter. 

d) The minimum valve capacity in pounds (ki- 
lograms) per hour shall be the greater of that 
determined by dividing the maximum Btu 
(Watts) output at the boiler nozzle obtained 
by the firing of any fuel for which the unit 
is installed by 1000 Btu/lb (645 W/hr/kg), 
or shall be determined on the basis of the 
pounds (kilograms) of steam generated 
per hour per square foot (square meter) 
of boiler heating surface as given in Table 
3.9.2. For cast-iron boilers, the minimum 
valve capacity shall be determined by the 
maximum output method. In many cases 
a greater relieving capacity of valves will 
have to be provided than the minimum 
specified by these rules. In every case, the 
requirement of 3.9.2(e) shall be met. 

e) The safety valve capacity for each steam 
boiler shall be such that with the fuel burn- 
ing equipment installed, and operated at 
maximum capacity, the pressure cannot 
rise more than 5 psig (34 kPa) above the 
maximum allowable working pressure. 

f) When operating conditions are changed, 
or additional boiler heating surface is 
installed, the valve capacity shall be in- 
creased, if necessary, to meet the new con- 
ditions and be in accordance with 3.9.2(e). 
The additional valves required, on account 
of changed conditions, may be installed 
on the outlet piping provided there is no 
intervening valve. 



3.9.3 SAFETY RELIEF VALVE 

REQUIREMENTS FOR HOT- 
WATER HEATING OR HOT- 
WATER SUPPLY BOILERS 

a) Safety relief valves are to be manufactured 
in accordance with a national or interna- 
tional standard. 

b) Each hot-water heating or hot-water sup- 
ply boiler shall have at least one National 
Board capacity certified safety relief valve, 
of the automatic reseating type set to relieve 
at or below the maximum allowable work- 
ing pressure of the boiler. 

c) Hot-water heating or hot-water supply 
boilers limited to a water temperature not 
in excess of 210°F (99°C) may have, in 
lieu of the valve(s) specified in (b) above, 
one or more National Board capacity certi- 
fied temperature and pressure safety relief 
valves of the automatic reseating type set to 
relieve at or below the maximum allowable 
working pressure of the boiler. 

d) When more than one safety relief valve is 
used on either hot-water heating or hot- 
water supply boilers, the additional valves 
shall be National Board capacity certified 
and may have a set pressure within a range 
not to exceed 6 psig (40 kPa) above the 
maximum allowable working pressure of 
the boiler up to and including 60 psig (41 4 
kPa), and 5% for those having a maximum 
allowable working pressure exceeding 60 
psig (41 3 kPa). 

e) No safety relief valve shall be smaller than 
NPS 3/4 (DN 20) nor larger than NPS 4 
(DN 1 00), except that boilers having a heat 
input not greater than 15,000 Btu/hr (4.4 
kW) should be equipped with a rated safety 
relief valve of NPS 1/2 (DN 15). 

f) The required relieving capacity, in pounds 
per hour (kg/hr), of the pressure relieving 
device or devices on a boiler shall be the 
greater of that determined by dividing the 
maximum output in Btu (Watts) at the boiler 
nozzle obtained by the firing of any fuel for 



56 



NATIONAL BDARD INSPECTION CODE • PART 1 



INSTALLATION 



A08 Table 3.9.2 - Minimum Pounds of steam per hour per square foot of 
Heating Surface 1 ib steam/hr/sq.ft (kg/hr/sq m) 







Firetube Boilers 


Watertube Boilers 




Boiler heating surface 




hand-fired 


5(24) 


6(29) 




stoker-fired 


7(34) 


8(39) 




oil, gas, or pulverized fuel-fired 


8(39) 


1 (49) 








Waterwall heating surface 




hand-fired 


8(39) 


8(39) 




stoker-fired 


1 (49) 


12 (59) 




oil, gas, or pulverized fuel-fired 


14(68) 


16(78) 








Copper-finned watertubes 


A08 


hand-fired 




4(20) 


A08 


stoker-fired 




5 (24) 


A08 


oil, gas, or pulverized fuel-fired 




6(29) 



A07 
A08 



A08 



A08 



NOTES: 

• When a boiler is fired only by a gas having a heat value not in excess of 200 Btu/cu.ft.(7.5MJ/cu. m), the mini- 
mum relieving capacity should be based on the values given for hand-fired boilers above. 

« The heating surface shall be computed for that side of the boiler surface exposed to the products of combustion, 
exclusive of the superheating surface. In computing the heating surface for this purpose only the tubes, fireboxes, 
shells, tubesheets, and the projected area of headers need to be considered, except that for vertical firetube steam 
boilers, only that portion of the tube surface up to the middle gage cock is to be computed. 

• For Firetube boiler units exceeding 8000 Btu/ft. 2 (9085 J/cm. 2 ) (total fuel Btu 0) Input divided by total heat- 
ing surface), the factor from the table will be increased by 1 (4.88) for every 1000 Btu/ft. 2 (1136 J/cm. 2 ) above 
8000 Btu/ft. 2 (9085 J/cm. 2 ) For units less than 7000 Btu/ft. 2 (7950 J/cm. 2 ), the factor from the table will be 
decreased by 1 (7950 J/cm. 2 ). 

• For watertube boiler units exceeding 1 6000 Btu/ft. 2 (1 81 70 J/cm. 2 )(total fuel BTU input divided by the total 
heating surface) the factor from the table will be increased by 1 (4.88) for every 1 000 Btu/ft. 2 (1136 J/cm. 2 ) 
above 1 6000 Btu/ft. 2 (1 81 70 J/cm. 2 ). For units with less than 1 5000 Btu/ft. 2 (1 7034 J/cm. 2 ), the factor in the 
table will be decreased by 1 (4.88) for every 1 000 Btu/ft. 2 (1 1 36 J/cm. 2 ) below 1 5000 Btu/ft. 2 (1 7034 J/cm. 2 ). 



which the unit is installed by 1000 Btu/lb 
(645 w/kg), or shall be determined on the 
basis of pounds (kilograms) of steam gener- 
ated per hour per square foot (square meter) 
of boiler heating surface as given in Table 
3.9.2. For cast-iron boilers, the minimum 
valve capacity shall be determined by the 
maximum output method. In many cases 
a greater relieving capacity of valves will 
have to be provided than the minimum 
specified by these rules. In every case, the 
requirements of 3.9.3(h) shall be met. 



g) When operating conditions are changed, 
or additional boiler heating surface is 
installed, the valve capacity shall be in- 
creased, if necessary, to meet the new 
conditions and shall be in accordance with 
3.9.3(h). The additional valves required, 
on account of changed conditions, may 
be installed on the outlet piping provided 
there is no intervening valve. 

h) Safety relief valve capacity for each boiler 
with a single safety relief valve shall be 



57 



NATIDNAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



such that, with the fuel burning equipment 
installed and operated at maximum capac- 
ity, the pressure cannot rise more than 1 0% 
above the maximum allowable working 
pressure. When more than one safety relief 
valve is used, the over pressure shall be 
limited to 10% above the set pressure of 
the highest set valve allowed by 3.9.3(b). 



3.9.4 SAFETY RELIEF VALVE 

REQUIREMENTS FOR POTABLE 

WATER HEATERS 

a) Each water heater shall have at least one 
National Board capacity certified tempera- 
ture and pressure safety relief valve. No 
safety relief valve shall be smaller than NPS 

3/4 (DN 20). 

b) The pressure setting shall be less than or 
equal to the maximum allowable working 
pressure of the water heater. However, if 
any of the other components in the hot-wa- 
ter supply system (such as valves, pumps, 
expansion or storage tanks, or piping) have 
a lesser working pressure rating than the 
water heater, the pressure setting for the 
safety relief valve(s) shall be based upon 
the component with the lowest maximum 
allowable working pressure rating. If more 
than one safety relief valve is used, the ad- 
ditional valve(s) may be set within a range 
not to exceed 1 0% over the set pressure of 
the first valve. 

c) The required relieving capacity in Btu/hr 
(W) of the safety relief valve shall not be 
less than the maximum allowable input 
unless the water heater is marked with the 
rated burner input capacity of the water 
heater on the casing in a readily visible 
location, in which case the rated burner 
input capacity may be used as a basis for 
sizing the safety relief valves. The relieving 
capacity for electric water heaters shall be 
3500 Btu/hr (1 .0 kW) per kW of input. In 
every case, the following requirements shall 
be met. Safety relief valve capacity for each 
water heater shall be such that with the fuel 
burning equipment installed and operated 



at maximum capacity, the pressure cannot 
rise more than 10% above the maximum 
allowable working pressure. 

d) If operating conditions are changed or addi- 
tional heating surface is installed, the safety 
relief valve capacity shall be increased, 
if necessary, to meet the new conditions 
and shall be in accordance with the above 
provisions. In no case shall the increased 
input capacity exceed the maximum allow- 
able input capacity. The additional valves 
required, on account of changed condi- 
tions, may be installed on the outlet piping 
providing there is no intervening valve. 



3.9.4.1 INSTALLATION 

Safety relief valves shall be installed by either 
the installer or the manufacturer before a water 
heater is placed in operation. 



3.9.4.2 PERMISSIBLE MOUNTINGS 

Safety relief valves shall be connected directly 
to a tapped or flanged opening in the top of 
the water heater, to a fitting connected to the 
water heater by a short nipple, to a Y-base, or 
to a valveless header connecting water outlets 
on the same heater. Safety relief valves shall be 
installed with their spindles upright and vertical 
with no horizontal connecting pipe, except that, 
when the safety relief valve is mounted directly 
on the water heater vessel with no more than 4 
in. (1 00 mm) maximum interconnecting piping, 
the valve may be installed in the horizontal po- 
sition with the outlet pointed down. The center 
line of the safety relief valve connection shall 
be no lower than 4 in. (1 00 mm) from the top 
of the shell. No piping or fitting used to mount 
the safety valve shall be of nominal pipe size 
less than that of the valve inlet. 



58 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



3.9.4.3 REQUIREMENTS FOR 

COMMON CONNECTION FOR 
TWO OR MORE VALVES 

a) When a potable water heater is fitted with 
two or more safety relief valves on one con- 
nection, this connection shall have a cross- 
sectional area not less than the combined 
areas of inlet connections of all the safety 
release valves with which it connects. 

b) WhenaY-base is used, the inlet area shall be 
not less than the combined outlet areas. 

c) When the size of the water heater requires 
a safety relief valve larger than NPS 4 (DN 
100) two or more valves having the re- 
quired combined capacity shall be used. 
When two or more valves are used on a 
water heater, they may be single, directly 
attached, or mounted on aY-base. 



3.9.4.4 THREADED CONNECTIONS 



of the valve outlets discharging thereinto, 
and shal I be as short and straight as possible 
and so arranged as to avoid undue stress 
on the valve or valves. When an elbow is 
placed on a safety relief discharge pipe, it 
shall be located close to the valve outlet. 

b) The discharge from safety relief valves shall 
be so arranged that there will be no danger 
of scalding attendants. When the safety re- 
lief valve discharge is piped away from the 
water heater to the point of discharge, there 
shall be provisions for properly draining 
the piping and valve body. The size and ar- 
rangement of discharge piping shall be such 
that any pressure that may exist or develop 
will not reduce the relieving capacity of 
the relieving devices below that required 
to protect the water heater. 



3.9.5 SAFETY AND SAFETY RELIEF 

VALVES FOR TANKS AND HEAT 
EXCHANGERS 



A threaded connection may be used for attach- 
ing a valve. 



3.9.5.1 



STEAM TO HOT-WATER SUPPLY 



3.9.4.5 



PROHIBITED MOUNTINGS 



Safety relief valves shall not be connected to an 
internal pipe in the water heater or a cold water 
feed line connected to the water heater. 



3.9.4.6 USE OF SHUTOFF VALVES 
PROHIBITED 



When a hot-water supply is heated indirectly 
by steam in a coil or pipe within the service 
limitations setforth in 3.2, Definitions, the pres- 
sure of the steam used shall not exceed the safe 
working pressure of the hot water tank, and a 
safety relief valve at least NPS 1 (DN 25), set 
to relieve at or below the maximum allowable 
working pressure of the tank, shall be applied 
on the tank. 



No shutoff of any description shall be placed 
between the safety relief valve and the water 
heater or on discharge pipes between such 
valves and the atmosphere. 



3.9.4.7 SAFETY RELIEF VALVE 
DISCHARGE PIPING 

a) When a discharge pipe is used, its internal 
cross-sectional area shall be not less than 
the ful I area of the valve outlet or of the total 



3.9.5.2 HIGH TEMPERATURE WATER TO 
WATER HEAT EXCHANGER 

When high temperature water is circulated 
through the coils or tubes of a heat exchanger 
to warm water for space heating or hot-water 
supply, within the service limitations set forth 
in 3.2, Definitions, the heat exchanger shall 
be equipped with one or more National Board 
capacity certified safety relief valves set to 
relieve at or below the maximum allowable 
working pressure of the heat exchanger, and 



59 



NATIDNAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



of sufficient rated capacity to prevent the heat 
exchanger pressure from rising more than 1 0% 
above the maximum allowable working pres- 
sure of the vessel. 



3.9.5.3 HIGH TEMPERATURE WATER TO 
STEAM HEAT EXCHANGER 

When high temperature water is circulated 
through the coi Is or tubes of a heat exchanger to 
generate low pressure steam, within the service 
limitations set forth in 3.2, Definitions, the heat 
exchanger shall be equipped with one or more 
National Board capacity certified safety valves 
set to relieve at a pressure not to exceed 1 5 psig 
(100 kPa), and of sufficient rated capacity to 
prevent the heat exchanger pressure from rising 
more than 5 psig (34 kPa) above the maximum 
allowable working pressure of the vessel. For 
heat exchangers requiring steam pressures 
greater than 1 5 psig (1 00 kPa), refer to Section 
2 or Section 4 of this Part. 



3.10.3 



BOILER INSTALLATION REPORT 



a) Upon completion, inspection, and accep- 
tance of the installation, the installer shall 
complete and certify the Boiler Installation 
Report 1-1. See 1.4.5.1. 

b) The Boiler Installation Report 1-1 shall be 
submitted as follows: 

1 ) One copy to the Owner; 

2) One copy to the Jurisdiction, if re- 
quired. 



3.10.4 



TABLES AND FIGURES 



3.10 



TESTING AND ACCEPTANCE 



a) Table 3.7.9.1 -a, Expansion Tank Capacities 
for Gravity Hot-Water Systems 

b) Table 3.7.9.1 -b, Expansion Tank Capacities 
for Forced Hot-Water Systems 

c) Table 3.7.9.1 -c, Expansion Tank Capacities 
for a Water Heater 



3.10.1 



PRESSURE TEST 



Prior to initial operation, the completed boiler, 
individual module, or assembled module, shall 
be subjected to a pressure test in accordance 
with the requirements of the original code of 
construction. 



d) Table 3.7.7.1 , Size of Bottom Blowoff Pip- 
ing, Valves, and Cocks 

e) Table 3 .9.2, Minimum Pounds of Steam Per 
Hour Per Square Foot of Heating Surface 

f) Figure 3 .3 . 1 . 1 -a, Spacing and Weld Details 
for Supporting Lugs in Pairs on Horizontal 
Return Tubular Boilers 



3.10.2 



FINAL ACCEPTANCE 



a) In addition to determining that all equip- 
ment called for is furnished and installed in 
accordance with the plans and specifica- 
tions, all controls shall be tested by a person 
familiar with the control system. 

b) Before any new heating plant (or boiler) is 
accepted for operation, a final (or accep- 
tance) inspection by a person familiar with 
the system shall be completed and all items 
of exception corrected. 



g) Figure 3.3.1 .1 -b, Welded Bracket Connec- 
tion for Horizontal-Return Tubular Boilers 

h) Figure 3.7.5-a, Steam Boilers in Battery - 
Pumped Return -Acceptable Piping Instal- 
lation 

i) Figure 3.7.5-b, Steam Boilers in Battery - 
Gravity Return - Acceptable Piping Instal- 
lation 

)) Figure 3.7. 5-c, Hot-Water Boilers in Battery 
-Acceptable Piping Installation 



SO 



N 



ATIDNAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



k) Figure 3 .7.5-6, Storage Potable Water Heat- 
ers in Battery - Acceptable Piping Installa- 
tion 

I) Figure 3.7. 5-e, FlowThrough Potable Water 
Heater Without Provision for Piping Expan- 
sion-Acceptable Piping Installation 



e i 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



G2 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



4.4.2 PRESSURE INDICATING 

DEVICES 

The need for pressure indicating devices should 
be considered in the design of the pressure 
vessel, and when required, the scale on the 
dial of the pressure gage shall be at least 25% 
above the highest set pressure of the pressure 
relief device. 



4.5.3 



LOCATION 



4.5 



PRESSURE RELIEF DEVICES 



All pressure vessels shall be protected by pres- 
sure relief devices in accordance with the fol- 
lowing requirements. 



4.5.1 



DEVICE REQUIREMENTS 



a) Pressure relief devices are to be manu- 
factured in accordance with a national or 
international standard and be certified for 
capacity (or resistance to flow for rupture 
disk devices) by the National Board. 

b) Dead weight or weighted lever pressure 
relief valves shall not be used. 

c) An unfired steam boiler shall be equipped 
with pressure relief valves as required in 
Section 2 of this Part. (See 2.9). 

d) Pressure relief devices shall be selected 
(i.e., material, pressure, etc.) and installed 
such that their proper functioning will not 
be hindered by the nature of the vessel's 
contents. 



4.5.2 



NUMBER OF DEVICES 



At least one device shall be provided for protec- 
tion of a pressure vessel. Pressure vessels with 
multiple chambers with different maximum al- 
lowable working pressures shall have a pressure 
relief device to protect each chamber under the 
most severe coincident conditions. 



a) The pressure relief device shall be installed 
directly on the pressure vessel, unless the 
source of pressure is external to the vessel 
and is under such positive control that the 
pressure cannot exceed the maximum over- A09 
pressure permitted by the original code of 
construction and the pressure relief device 
cannot be isolated from the vessel, except 

as permitted by 4.5.6 e) 2). 

b) Pressure relief devices intended for use in 
compressible fluid service shall be con- 
nected to the vessel in the vapor space 
above any contained liquid or in the piping 
system connected to the vapor space. 

c) Pressure relief devices intended for use in 
liquid service shall be connected below the 
normal liquid line. 



4.5.4 



CAPACITY 



a) The pressure relief device(s) shall have suf- 
ficient capacity to ensure that the pressure 
vessel is not exposed to pressure greater 
than that specified in the original code of 
construction. 

b) If an additional hazard can be created by 
exposure of a pressure vessel to fire or 
other unexpected source of external heat, 
supplemental pressure relief devices shall 
be installed to provide any additional ca- 
pacity that should be required. 

c) Vessels connected together by a system of 
piping not containing valves that can isolate 
any pressure vessel should be considered 
as one unit when determining capacity 
requirements. 

d) Heat exchangers and similar vessels shall 
be protected with a pressure relief device 
of sufficient capacity to avoid overpressure 
in case of internal failure. 



e) When a non-reclosing device is installed 



65 



NATIONAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



between a pressure relief valve and the 
pressure vessel, the reduction in capacity 
due to installation of the non-reclosing 
device shall be determined in accordance 
with the code of construction by use of 
a National Board certified Combination 
Capacity Factor (CCF). For rupture disks, 
if a certified combination capacity factor 
is not available, the capacity of the pres- 
sure relief valve shall be multiplied by 0.9 
and this value used as the capacity of the 
combination installation. 

f) The owner shall document the basis for 
selection of the pressure relief devices 
used, including capacity, and have such 
calculations available for review by the 
Jurisdiction. 



b) A non-reclosing device installed between a 
pressure vessel and a pressure relief valve 
shall meet the requirements of 4.5.6(a). 

c) The opening in the pressure vessel wall 
shall be designed to provide unobstructed 
flow between the vessel and its pressure 
relief device. 

d) When two or more required pressure relief 
devices are placed on one connection, the 
inlet cross-sectional area of this connection 
shall be sized either to avoid restricting 
flow to the pressure relief devices or made 
at least equal to the combined inlet areas 
of the pressure relief devices connected to 
it. The flow characteristics of the upstream 
system shall satisfy the requirements of 
4.5.6(a). 



4.5.5 



SET PRESSURE 



a) When a single pressure relief device is used, 
the set pressure marked on the device shall 
not exceed the maximum allowable work- 
ing pressure. 

b) When more than one pressure relief device 
is provided to obtain the required capacity, 
only one pressure relief device set pressure 
needs to be at the maximum allowable 
working pressure. The set pressures of the 
additional pressure relief devices shall be 
such that the pressure cannot exceed the 
overpressure permitted by the code of con- 
struction. 



4.5.6 INSTALLATION AND 

DISCHARGE PIPING 
REQUIREMENTS 

a) The opening through all pipe and fittings 
between a pressure vessel and its pressure 
relief device shall have at least the area of 
the pressure relief device inlet. The char- 
acteristics of this upstream system shall be 
such that the pressure drop will not reduce 
the relieving capacity below that required 
or adversely affect the proper operation of 
the pressure relief device. 



e) There shall be no intervening stop valves 
between the vessel and its pressure relief 
device(s), or between the pressure relief 
device(s) and the point of discharge, except 
under the following conditions: 

1) When these stop valves are so con- 
structed or positively controlled that 
the closing of the maximum number of 
block valves at one time will not reduce 
the pressure relieving capacity below 
the required relieving capacity; or, 

2) Upon specific acceptance of the Ju- 
risdiction, when necessary for the 
continuous operation of processing 
equipment of such a complex nature 
that shutdown of any part is not fea- 
sible, a full area stop valve between a 
pressure vessel and its pressure relief 
device should be provided for inspec- 
tion and repair purposes only. This stop 
valve shall be arranged so that it can 
be locked or sealed open, and it shall 
not be closed except by an authorized 
person who shall remain stationed there 
during that period of operation while 
the valve remains closed. The valve 
shall be locked or sealed in the open 
position before the authorized person 
leaves the station. 



66 



NATIONAL BDARD INSPECTION CODE • PART 1 



INSTALLATION 



3) A full area stop valve should also be 
placed on the discharge side of a pres- 
sure relief device when its discharge 
is connected to a common header 
for pressure relief devices to prevent 
discharges from these other devices 
from flowing back to the first device 
during inspection and repair. This stop 
valve shall be arranged so that it can 
be locked or sealed open, and it shall 
not be closed except by an authorized 
person who shall remain stationed there 
during that period of operation while 
the valve remains closed. The valve 
shall be locked and sealed in the open 
position before the authorized person 
leaves the station. This valve shall only 
be used when a stop valve on the inlet 
side of the pressure relief device is first 
closed. 

4) A pressure vessel in a system where 
the pressure originates from an out- 
side source should have a stop valve 
between the vessel and the pressure 
relief device, and this valve need not 
be sealed open, provided it also closes 
off that vessel from the source of the 
pressure. 

A09 5) Pressure vessels designed for human 
occupancy (such as decompression 
or hyperbaric chambers) shall be pro- 
vided with a quick opening stop valve 
between the pressure vessel and its 
pressure relief valve. The stop valve 
shall be normally sealed open with a 
frangible seal and be readily accessible 
to the pressure relief attendant. 

f) Pressure relief device discharges shall be 
arranged such that they are not a hazard to 
personnel or other equipment and, when 
necessary, lead to a safe location for dis- 
posal of fluids being relieved. 

g) Discharge lines from pressure relief devices 
shall be designed to facilitate drainage or 
be fitted with drains to prevent liquid from 
collecting in the discharge side of a pres- 
sure relief device. The size of discharge 



lines shall be such that any pressure that 
may exist or develop will not reduce the 
relieving capacity of the pressure relief 
device or adversely affect the operation of 
the pressure relief device. 

h) Pressure relief devices shall be installed so 
they are readily accessible for inspection, 
repair, or replacement. 



4.6 



TESTING AND ACCEPTANCE 



a) The installer shall exercise care during 
installation to prevent loose weld mate- 
rial, welding rods, small tools, and miscel- 
laneous scrap metal from getting into the 
vessel. The installer shall inspect the interior 
of the vessel and its appurtenances where 
possible prior to making the final closures 
for the presence of foreign debris. 

b) The completed pressure vessel shall be 
pressure tested in the shop or in the field 
in accordance with the original code of 
construction. When required by the Juris- 
diction, owner or user, the Inspector shall 
witness the pressure test of the completed 
installation, including piping to the pressure 
gage, pressure relief device, and, if present, 
level control devices. 



67 



NATIONAL BDARD INSPECTION CODE • PART 1 — INSTALLATION 



&B 



NATIONAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



5.2.5 



MATERIALS 



5.2.9 



BOLTING 



A08 



All materials for piping and its appurtenances 
shall comply with the requirements of the code 
of construction. 



5.2.6 



HANGERS AND SUPPORTS 



A07 Support of piping shall consider loads (includ- 
ing wind and seismic loads) imposed on equip- 
ment or existing piping to which it is attached. 
Non-piping attachments such as ladders and 
walkways, equipment supports, temporary 
supports, structural supports, etc., shall not be 
connected to the piping unless such loads have 
been considered in the design of the piping and 
its supports. Design of hangers and supports 
for piping shall consider loads imposed by 
hydrostatic pressure testing. The installer shall 
remove pins from non-rigid hangers and seal 
plugs from hydraulic snubbers and temporary 
supports used for installation prior to placing 
the piping in service. 



5.2.7 



PROTECTION AND CLEANING 



The installer shall exercise care during instal- 
lation to prevent loose weld material, welding 
rods, small tools, and miscellaneous scrap 
metal from getting into the piping. The installer 
shall inspect, and where necessary clean the in- 
terior of the piping and its appurtenances where 
possible, prior to making the final closures for 
the presence of foreign debris. 



All mechanical joints and connections shall 
conform to manufacturers' installation instruc- 
tions and recognized standards acceptable to 
the Jurisdiction having authority. 



5.3 



PRESSURE RELIEF DEVICES 



When required by the original code of con- 
struction, piping shall be protected by pressure 
relief devices in accordance with the following 
requirements. 



5.3.1 



DEVICE REQUIREMENTS 



5.2.8 



WELDING AND BRAZING 



a) Pressure relief devices are to be manu- 
factured in accordance with a national or 
international standard and be certified for 
capacity (or resistance to flow for rupture 
disc devices) by the National Board. 

1) In certain cases piping standards per- 
mit the use of regulators, which may 
include integral pressure relief valves 
to limit the pressure in a piping system. 
In this case, capacity certification of the 
pressure relief valve is not required. 

b) Dead weight or weighted lever pressure 
relief devices shall not be used. 

c) Pressure relief devices shall be selected 
(i.e., material, pressure, etc.) and installed 
such that their proper functioning will not 
be hindered by the nature of the piping 
system's contents. 



The installer should consider the impact of 
performing any preheating, welding, brazing, 
or postweld heat treatment on valves, instru- 
mentation, or other heat sensitive equipment 
and, where appropriate, review the equipment 
manufacturer's recommended installation pro- 
cedures prior to performing the work. 



5.3.2 



NUMBER OF DEVICES 



At least one pressure relief device shall be pro- 
vided for protection of a piping system. A pres- 
sure relief device installed on a pressure vessel 
or other component connected to the piping 
system should be used to meet this require- 
ment. Portions of piping systems with different 
maximum allowable working pressures shall 
have a pressure relief device to protect each 
portion separately. 



7 1 



NATIONAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



5.3.3 



LOCATION 



Pressure relief devices, except those covered by 
Sections 2 and 3 of this Part, may be installed 
at any location in the system provided the 

A09 pressure in any portion of the system cannot 
exceed the maximum overpressure permitted 
by the original code of construction. Pres- 
sure drop to the pressure relief device under 
flowing conditions shall be considered when 
determining pressure relief device location. 

A09 The pressure-relief device shall not be isolated 
from the piping system except as permitted by 
5.3.6 e). 



5.3.4 



CAPACITY 



a) The pressure relief device(s) shall have suf- 
ficient capacity to ensure that the piping is 
not exposed to pressures greater than that 
specified in the original code of construc- 
tion. 

b) When a non-reclosing device is installed 
between a pressure relief valve and the 
pipe, the reduction in capacity due to in- 
stallation of the non-reclosing device shall 
be determined in accordance with the code 
of construction by use of a National Board 
certified Combination Capacity Factor 
(CCF). For rupture disks, if a certified com- 
bination capacity factor is not available, the 
capacity of the pressure relief valve shall be 
multiplied by 0.9 and this value used as the 
capacity of the combination installation. 

c) The owner shall document the basis for 
selection of the pressure relief devices 
used, including capacity, and have such 
calculations available for review by the 
Jurisdiction, when required. 



5.3.5 



SET PRESSURE 



When a single pressure relief device is used, 
the set pressure marked on the device shall 
not exceed the maximum allowable work- 
ing pressure, except when allowed by the 
original code of construction. 



b) When more than one pressure relief device 
is provided to obtain the required capacity, 
only one pressure relief device set pressure 
needs to be at the maximum allowable 
working pressure. The set pressures of the 
additional pressure relief devices shall be 
such that the pressure cannot exceed the 
overpressure permitted by the code of con- 
struction. 



5.3.6 INLET AND DISCHARGE PIPING 

REQUIREMENTS 

a) The opening through all pipes and fittings 
between a piping system and its pressure 
relief device shall have at least the area of 
the pressure relief device inlet. The char- 
acteristics of this upstream system shall be 
such that the pressure drop will not reduce 
the relieving capacity below that required 
or adversely affect the operation of the pres- 
sure relief device. 

b) A non-reclosing device installed between 
a piping system and a pressure relief valve 
shall meet the requirements of 5.3.6(a). 

c) The opening in the pipe shall be designed 
to provide unobstructed flow between the 
pipe and its pressure relief device. 

d) When two or more required pressure relief 
devices are placed on the connection, the 
inlet cross-sectional area of this connection 
shall be sized either to avoid restricting 
flow to the pressure relief devices or made 
at least equal to the combined inlet areas 
of the pressure relief devices connected to 
it. The flow characteristics of the upstream 
system shall satisfy the requirements of 
5.3.6(a). 

e) There shall be no intervening stop valves 
between the piping system and its pressure 
relief device(s), or between the pressure 
relief device(s) and the point of discharge 
except under the following conditions: 



72 



NATIDNAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



3) 



When these stop valves are so con- 
structed or positively controlled that 
the closing of the maximum number of 
block valves at one time will not reduce 
the pressure relieving capacity below 
the required relieving capacity; or, 

Upon specific acceptance of the Ju- 
risdiction, when necessary for the 
continuous operation of processing 
equipment of such a complex nature 
that shutdown of any part is not fea- 
sible, a full area stop valve between 
a piping system and its pressure relief 
device should be provided for inspec- 
tion and repair purposes only. This stop 
valve shall be arranged so that it can 
be locked or sealed open and it shall 
not be closed except by an authorized 
person who shall remain stationed there 
during that period of operation while 
the valve remains closed. The valve 
shall be locked or sealed in the open 
position before the authorized person 
leaves the station. 

A full area stop valve may be placed on 
the discharge side of a pressure relief 
device when its discharge is connected 
to a common header for pressure relief 
devices to prevent discharges from 
these other devices from flowing back 
to the first device during inspection and 
repair. This stop valve shall be arranged 
so that it can be locked or sealed open, 
and it shall not be closed except by an 
authorized person who shall remain 
stationed there during that period of op- 
eration while the valve remains closed. 
The valve shall be locked or sealed in 
the open position before the authorized 
person leaves the station. This valve 
shall only be used when a stop valve 
on the inlet side of the pressure relief 
device is first closed. 



provided it also closes off that vessel 
from the source of pressure. 

f) Pressure relief device discharges shall be 
arranged such that they are not a hazard to 
personnel or other equipment and, when 
necessary, lead to a safe location for dis- 
posal of fluids being relieved. 

g) Discharge lines from pressure relief devices 
shall be designed to facilitate drainage or 
be fitted with drains to prevent liquid from 
collecting in the discharge side of a pres- 
sure relief device. The size of discharge 
lines shall be such that any pressure that 
may exist or develop will not reduce the 
relieving capacity of the pressure relief 
device or adversely affect the operation of 
the pressure relief device. 

h) The reaction forces due to discharge of A09 
pressure relief devices shall be considered 
in the design of the inlet and discharge 
piping. 

I) Pressure relief devices shall be installed so A09 
they are accessible for inspection, repair, 
or replacement. 



5.4 EXAMINATION, INSPECTION, 

AND TESTING 

The owner shall ensure that all examinations, 
inspections, and tests required by the code 
of construction have been performed prior to 
operation. 



4) A piping system where the pressure 
originates from an outside source 
should have a stop valve between the 
system and the pressure relief device, 
and this valve need not be sealed open, 



73 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



74 



NATIONAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



A07 b) Design documentation, called the "De- 
rate Curve," is required which dictates the 
maximum allowable operating parameters 
as shell thickness is reduced (see Figure 
S1 .1 ). Calculations, used to determine those 

A07 parameters, are in accordance with ASME 
Code requirements for primary membrane 
stress by the vessel manufacturer or design 
criteria based on relevant stress categories, 
e.g., fatigue and maximum principal stress. 
Calculation of these parameters requires 
that the respective stresses, resulting from 
the imposed loads, be compared to the 
appropriate material strength properties. 
Hence, knowledge of the applied stresses in 
the shell and the tensile and fatigue proper- 
ties of the material are essential. 

c) Yankee dryers are subjected to a variety of 

loads that create several categories of stress. 

Yankee dryers are designed such that the 

stress of greatest concern occurs at the 

A07 centerline of the shell. 

1) Steam Pressure Load — The internal 
steam pressure is one of the principal 
design loads applied to the Yankee 
dryer. The steam pressure expands the 
shell radially, causing a predominately 
circumferential membrane tensile 
stress. Because the shell is constrained 
radially by the heads at either end of the 
shell, the steam pressure also causes a 
primary bending stress in the vicinity of 
the head-to-shell joint. The ends of the 
shell are in tension on the inside and 
compression on the outside due to the 
steam pressure. The steam pressure also 
causes a bending stress in the heads. 

2) Inertia Load — The rotation of the 
Yankee dryer causes a circumferential 
membrane stress in the shell similar to 
that caused by the pressure load. This 
stress is included in the design of the 
shell and increases with dryer diameter 
and speed. 



3) Thermal Load — The wet sheet, applied A07 
to the shell, causes the outside surface 

to cool and creates a thermal gradient 
through the shell wall. This thermal 
gradient results in the outside surface 
being in tension and the inside surface 
in compression. With this cooling, the 
average shell temperature is less than 
the head temperature, which creates 
bending stresses on the ends of the 
shell and in the heads. The ends of the 
shell are in tension on the outside and 
compression on the inside. 

a. Other thermal loadings also oc- 
cur on a Yankee dryer. The use of 
full-width showers for a variety of 
papermaking purposes affects the 
shell similar to a wet sheet. The use 
of edge sprays produce high bend- 
ing stress in the ends of the shell 
due to the mechanical restraint of 
the heads. 

b. Warm-up, cool-down, hot air im- 
pingement from the hood, moisture 
profiling devices, fire fighting, and 
wash-up can all produce non-uni- 
form thermal stresses in the pres- 
sure containing parts of the Yankee 
dryer. Heating or cooling different 
portions of the Yankee dryer at dif- 
ferent rates causes these non-uni- 
form stresses. 

4) Nip Load — The nip load from the A07 
contacting pressure roll(s) results in an 
alternating, high cycle, bending stress 

in the shell. This stress is greatest at 
the centerline of the shell. The load of 
the pressure roll deflects the shell radi- 
ally inward causing a circumferential 
compressive stress on the outside sur- 
face and a tensile stress on the inside. 
Because the shell has been deflected 
inward atthe pressure roll nip, it bulges 
outward about 30 degrees on each side 
of the nip. The outward bulge causes a 
tensile stress on the outside shell sur- 



79 



NATIONAL BDARD INSPECTION CODE • PART 1 — INSTALLATION 



S1.4 



face at that location and a correspond- 
ing compressive stress on the inside. 
Since the shell is passing under the 
pressure roll, its surface is subjected to 
an alternating load every revolution. 



ASME CODE PRIMARY 
MEMBRANE STRESS CRITERIA 



A07 



Yankee dryers are typically designed and 
fabricated in accordance with Section VIII, 
Division 1, of the ASME Pressure Vessel 
Code. The maximum allowable stress for 
cast iron is specified in UCI-23 and UC-22 
of the ASME Code. 

b) Section VIII, Division 1, requires design 
stresses to be calculated such that any 
combination of loading expected to occur 
simultaneously during normal operation of 
the Yankee dryer will not result in a general 
primary stress exceeding the maximum 
allowable stress value of the material. In 
the ASME Code, the combination of load- 
ing resulting in the primary membrane 

A07 stress in the shell is interpreted to be only 
composed of the circumferential stress 
from steam pressure. Sometimes, the stress 
from the inertial loading is included in this 
consideration. 

c) In Section VIII, Division 1, it is very im- 
portant to note that no formulas are given 
for determining the stresses from thermal 

A07 operating loads and pressure roll nip 
load(s). Hence, additional criteria need to 
be incorporated to establish the maximum 
allowable operating parameters of the Yan- 
kee dryer. Two such additional criteria are 
based upon the maximum principal and 
fatigue stress. 

1) Maximum Principal Stress Criteria 

A07 The maximum principal stress in aYan- 

kee dryer shell is the sum of the stresses 

that are simultaneously applied to the 

shell and is always aligned in the cir- 

A07 cumferential direction. The purpose of 



these criteria is to recognize the paper 
making application of the Yankee dryer 
and to prevent catastrophic failure by 
including all stresses. The ASME Code 
does not provide specific formulas 
for the full array of Yankee dryer shell 
stresses encountered in tissue making. 



A07 



2) Fatigue Stress Criteria 

Under normal operation, the stresses 
due to the steam pressure, inertial and 
thermal operating loads are considered 
to be steady-state stresses. When act- 
ing simultaneously, the sum of these 
stresses must be judged against the 
cyclic, or alternating, stress due to the A07 
pressure roll nip load. Fatigue stress 
criteria limit the alternating stress at a 
given mean stress using fatigue failure 
criteria described by the Goodman or 
Smith Diagram. The purpose of this 
limitation is to prevent crack initiation 
in the outside wall due to the combina- 
tion of stresses. As the thickness of the 
shell is reduced, one or more of these A07 
criteria will control the various operat- 
ing parameters. 



S1.5 PRESSURE TESTING 

a) Water pressure testing in the field is not A07 
recommended because of the large size of 
Yankee dryers and the resulting combined 
weight of the Yankee dryer and the water 
used in the testing. This combined weight A07 
can lead to support structure overload. Sev- 
eral failures ofYankee dryers have occurred 
during field pressure testing using water. If A07 
this test must occur, the following review 
is recommended: 



The testing area should be evaluated for 
maximum allowable loading, assum- 
ing the weight of the Yankee dryer, the 
weight of the water filling the Yankee 
dryer, and the weight of the support 
structure used to hold the Yankee dryer 
during the test. 



A07 



so 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



A07 2) The manufacturer should be contacted 
to provide information on building the 
Yankee dryer support structure for the 
water pressure test. Typically, the Yan- 
kee dryer is supported on saddles that 
contact the Yankee dryer shell at each 
end near the head-to-shell joint. The 
manufacturer can provide information 
on saddle sizing and location so that 
the Yankee dryer is properly supported 
for the test. 

A07 b) When pressure testing is desired to evalu- 
ate the Yankee dryer for fitness for service, 
an alternative to water pressure testing is 
acoustic emission testing using steam or air 
pressure. Typically, the test pressure used is 

A q 7 the operating pressure. Caution needs to be 
exercised to ensure personnel safety. Entry 
to the test area needs to be controlled and 

A07 all personnel need to maintain a safe dis- 
tance from the Yankee dryer during the test. 

^07 The steam or air test pressure should never 
exceed the Maximum Allowable Working 
Pressure (MAWP) of the Yankee dryer. 



Acoustic Emmission Testing can be used to 
locate and determine if a linear indication 
is active, e.g., propagating crack. Metal lo- 
graphic analysis is useful in differentiating 
between original casting discontinuities 
and cracks. 

c) When nondestructive testing produces an 
indication, the indication is subject to inter- 
pretation as false, relevant, or nonrelevant. 
If it has been interpreted as relevant, the 
necessary subsequent evaluation will result 
in a decision to accept, repair, replace, 
monitor, or adjust the maximum allowable 
operating parameters. 



S1.6 NONDESTRUCTIVE 

EXAMINATION 

a) Nondestructive examination (NDE) meth- 
A07 ods should be implemented by individuals 
qualified and experienced with the material 
to be tested using written NDE procedures. 
ForYankee dryers, cast iron knowledge and 
experience are essential. 

A07 b) Typical nondestructive examination meth- 
ods should be employed to determine 
indication length, depth, and orientation 
(sizing) of discontinuities in Yankee Dryers. 
Magnetic particle, specifically the wet fluo- 

A07 rescent method, and dye penetrant methods 
are applicable in the evaluation of surface- 
breaking indications. Ultrasound testing 
is the standard method for evaluation of 
surface-breaking and embedded indica- 
tions. Radiographic methods are useful in 
the evaluation of embedded indications. 



B 1 



NATIDNAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



SUPPLEMENT 2 

SAFETY VALVES ON THE LOW- 
PRESSURE SIDE OF STEAM 
PRESSURE-REDUCING VALVES 



S2.1 



SCOPE 



a) The subject of protection of vessels in steam 
service connected to the low-pressure side 
of a steam-pressure-reducing valve is of 
considerable importance to proper opera- 
tion of auxiliary equipment such as pressure 
cookers, hot-water heating systems, etc., 
operating at pressures below that which the 
primary boiler generating unit is operating. 

b) To automatically reduce the primary boiler 
pressure for such processing equipment, 
pressure-reducing valves are used. The 
manufacturers of such equipment have 
data available listing the volume of flow 
through reducing valves manufactured by 
them, but such data are not compiled in a 
form that the results can be deduced read- 
ily. To protect the equipment operating on 
the low pressure side of a pressure-reducing 
valve, safety valves of a relieving capacity 
sufficient to prevent an unsafe pressure rise 
in case of failure of the pressure-reducing 
valve, should be installed. 

c) The pressure-reducing valve is a throttling 
device, the design of which is based on 
certain diaphragm pressures opposed by 
spring pressure which, in turn, controls the 
opening through the valve. If the spring, 
the diaphragm, or any part of the pres- 
sure-reducing valve fails, steam will flow 
directly through the valve and the low 
pressure equipment will be subjected to 
the boiler pressure. To protect the equip- 
ment operating on the low pressure side of 
the pressure-reducing valve, safety valve(s) 
should be installed on the low pressure side 
of the pressure-reducing valve, which will 
provide a relieving capacity sufficient to 
prevent the pressure from rising above the 
system design pressure. 



d) In most cases pressure-reducing valves used 
for the reduction of steam pressures have 
the same pipe size on the inlet and outlet. 
In case of failure of a pressure-reducing 
valve, the safety valve on the low-pressure 
side must have a capacity to take care of 
the volume of steam determined by the high 
pressure side and the area of the pipe. 



S2.2 



SAFETY VALVE CAPACITY 



a) The capacity of the safety valve(s) on the 
low-pressure side of the pressure-reducing 
valve should be based on the capacity of 
the pressure-reducing valve when wide 
open or under maximum flow conditions 
or the flow capacity through the bypass 
valve. 

b) By using the formula inS2.3 below, Inspec- 
tors may calculate the required relieving 
capacities of the safety valve(s) installed 
on the low-pressure side of the pressure- 
reducing valve. 

c) Usually a pressure-reducing valve has 
a bypass arrangement so that in case of 
failure of the pressure-reducing valve the 
boiler pressure may be short circuited 
into the low-pressure line without passing 
through the pressure-reducing valve. When 
determining the required relieving capacity 
of safety valves for the low-pressure side 
of the pressure-reducing valve, the steam 
flow through the bypass must be taken into 
consideration. 



S2.3 CALCULATION OF SAFETY 

VALVE RELIEVING CAPACITY 

a) When a pressure-reducing valve is in- 
stalled, there are two possibilities of intro- 



82 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



A09 



b) 



A09 



A09 



A09 



A09 



ducing boiler pressure into the low-pressure 
system: 

1) the failure of the pressure-reducing 
valve so that it remains wide open; 
and 

2) the possibility of the bypass valve being 
open. 

It is necessary therefore, to determine the 
flow under both circumstances in phara- 
graph a) above and check that the size of 
the safety valve under either condition will 
be adequate. The following formula should 
be used: 

1 ) steam flow, W in Ibs/hr (kg/hr) through 
the pressure-reducing valve 

W = AKC 

where, 

A = internal area in sq. in. (sq. mm) of 
the inlet pipe size of the pressure- 
reducing valve (see S2.5) 

K = flow coefficient for the pressure- 
reducing valve (see S2.4) 

C = flow of saturated steam through 
a 1 sq. in. (1 sq. mm) pipe at 
various pressure differentials from 
Tables S2.3-a, S2.3-b, or S2.3-C. 
(for U.S. Customary units) orTables 
S2.3M-a / S2.3M-b,orS2.3M-c(for 
metric units). 

2) steam flow, W in Ibs/hr (kg/hr) through 
the by-pass valve 



S2.4 



b) 



K ( = flow coefficient for the bypass A09 
valves (see S2.4) 

C 1 = flow of saturated steam through 
a 1 sq. in. (1 aq. mm) pipe at 
various pressure differentials from 
Tables S2.3-a, S2.3-b, or S2.3-C. 
(for U.S. Customary units) orTables 
S2.3M-a, S2.3M-b, or S2.3M-C ( for 
metric units). 



STEAM FLOW WHEN FLOW 
COEFFICIENTS ARE NOT 

KNOWN 



It is possible that the flow coefficients K and 
K 1 may not be known and in such instances 
for approximating the flow, a factor of 1/3 
may be substituted for K and 1/2 for K r 

The formulas in S2.3 then becomes: 

W = 1/3 AC for the capacity through the 
pressure-reducing valve; and 

W = 1/2 A 1 C, for the capacity through the 
bypass valve. 

Caution should be exercised when substitut- 
ing these factors for the actual coefficients 
since this method will provide approximate 
values only and the capacities so obtained 
may in fact be lower than actual. It is rec- 
ommended that the actual flow coefficient 
be obtained from the pressure-reducing 
valve manufacturer and reference books 
be consulted for the flow coefficient of the 
bypass valve. 



W = A, l< 1 C, 



A09 



where, 

A, = internal area in sq. in. (sq. mm) of 
the pipe size of the bypass around 
the pressure-reducing valve 



83 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



TABLE S2.3-a 














Capacity of Saturated Steam, in lb./hr., per sq. in. 


of Pipe Area 










Outlet 

pres., 
psi 




Pressure-reducing valve in 


et pressure, psi 










1500 1450 1400 1350 


1300 1250 1200 


1150 1100 


1050 


1000 


950 


900 


1000 


76560 72970 69170 64950 


60540 55570 49930 


43930 35230 


25500 








950 


77430 74180 70760 67000 


63100 58770 53920 


48610 42380 


34890 


24910 






900 


77750 74810 71720 68340 


64870 61040 56820 


52260 47050 


41050 


33490 


23960 




850 


77830 74950 72160 69130 


66020 62610 58900 


54930 50480 


45470 


39660 


29080 


23190 


800 


75070 72330 69490 


66700 63680 60390 


56910 53060 


48800 


43980 


38340 


31610 


750 


69610 


66880 64270 61260 


58200 54840 


51170 


47080 


42420 


37110 


700 




66900 64270 61520 


58820 55870 


52670 


49170 


45230 


40860 


650 




61550 


58860 56260 


53480 


50440 


47070 


43400 


600 






58980 562 70 


53660 


51020 


48470 


45010 


550 








53810 


51040 


48470 


45800 


500 














45850 


450 














45870 


400 
















350 
















300 
















250 
















200 
















175 
















150 
















125 
















110 
















100 
















85 
















75 
















60 
















50 
















40 
















30 
















25 
















15 
















10 
5 
















Where 


capacities are not shown for in 


et and outlet conditions, use the highest capacity shown unde 


r the 


applicable inlet pressure column. 















TABLE S2.3M-a 

Capacity of Saturated Steam, in kg/hr., per sq. mm of Pipe Area 



pres., 
MPa 



Pressure-reducing valve inlet pressure, MPa 



9.75 



9.50 



9.25 



9.00 



8.7S 



8.50 



8.25 



0.00 



7.75 



7.50 



7.25 



6.75 
6.50 

6.25 
6.00 
5.75 
5.30 
5.25 
5.00 
4.75 
4.50 
4.25 
4.00 
3.75 
3.50 
3.25 
3.00 



49.82 
50.52 
50.96 
51.19 
51.32 
51.40 



47.85 
48.69 
49.27 
49.62 
49.85 
49.97 
50.00 
50.01 



45.77 
46.79 
47.51 
47.99 
48.33 
48.53 
48.60 
48.62 



43.63 
44.83 
45.71 
46.33 
45.80 
47.11 
47.20 
47.23 
47.24 



41.28 
42.69 
43.75 
44.53 
45.14 
45.60 
45.82 
45.89 



38.73 
40.40 
41.67 
42.63 
43.40 
44.00 
44.35 
44.49 
44.52 
44.53 



36.01 
37.95 
39.46 
40.62 
41.56 
42.32 
42.78 
43.02 
43.13 
43.14 
43.15 



33.09 
35.30 
37.08 
38.74 
39.62 
40.55 
41.17 
41 .55 
41.75 
41.77 
41.82 
41.84 



29.47 
32.33 
34.46 
36.12 
37.51 
38.56 
39.44 
39.98 
40.31 
40.43 
40.46 
40.48 



25.37 
29.02 
31.59 
33.59 
35.25 
36.63 
37.62 
38.33 
38.81 
39.08 
39.10 
39.12 
39.14 



20.89 
25.31 
28.43 
30.83 
32.82 
34.48 
35.68 
36.57 
37.22 
37.63 
37.74 
37.82 
37.88 



20.46 
24.45 
27.53 
30.04 
32.05 
33.52 
34.64 
35.50 
36.07 
36.33 
36.45 
36.48 



19.36 
23.13 
26.20 
29.37 
31.16 
32.56 
33.64 
34.41 
34.90 
35.12 
35.13 



17.64 
21.90 
26.41 
28.59 
30.01 
31.66 
32.65 
33.39 
33.76 
33.81 



18.76 
23.01 
25.72 
27.84 
29.51 
30.76 
31.60 
32.15 
32.45 
32.47 
32.48 



Where capacities are not shown for inlet and outlet conditions, use the highest capacity shown under the applicable inlet 
pressure column. 



84 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



S2.5 TWO-STAGE PRESSURE- 

REDUCING VALVE STATIONS 



The safety relief valve for two-stage pressure- 
reducing valve stations shall be sized on the 
basis of the high-side pressure and the inlet 
size of the first pressure-reducing valve in the 
line. If an intermediate pressure line is taken off 
between the pressure-reducing valves, then this 
line and the final low side shall be protected 
by safety relief valves sized on the basis of the 
high-side pressure and the inlet size of the first 
pressure-reducing valve. See Table S2.5. 



TABLE S2.5 
Pipe Data 



Nominal 
Pipe Size, 

Unit Less 

(ANSI 

B36.10) 


Nominal 
Pipe Size, 
Unit Less 
(ISO 
3607) 


Average 
Outside 
Diameter, 
in. 


Average 
Outside 
Diameter, 

mm 


Nominal Wall 
Thickness of 
Standard 
Weight Pipe, 
in. 


Nominal Wall 
Thickness of 
Standard 
Weight Pipe, 
mm 


Approx. 
Internal 

Area, 
sq. in. 


Approx. 
Internal 
Area, 
sq. mm 


NPS 3/8 


DN 10 


0.675 


9.53 


0.091 


2.311 


0.191 


124 


NPS 1/2 


DN 15 


0.840 


12.7 


0.109 


2.769 


0.304 


198 


NPS 3/4 


DN20 


1.050 


19.1 


0.113 


2.870 


0.533 


347 


NPS1 


DN25 


1.315 


25.4 


0.133 


3.378 


0.864 


562 


NPS 1-1/4 


DN32 


1.660 


38.1 


0.140 


3.556 


1.50 


973 


NPS 1-1/2 


DN40 


1.900 


50.8 


0.145 


3.683 


2.04 


1324 


NPS 2 


DN50 


2.375 


63.5 


0.154 


3.912 


3.36 


2182 


NPS 2-1/2 


DN 65 


2.875 


76.2 


0.203 


5.516 


4.79 


3113 


NPS 3 


DN80 


3.500 


88.9 


0.216 


5.486 


7.40 


4807 


NPS 3-1/2 


DN90 


4.000 


114.3 


0.226 


5.740 


9.89 


6429 


NPS 4 


DN 100 


4.500 


136.5 


0.237 


6.020 


12.73 


8278 


NPS 5 


DN 125 


5.563 


141.3 


0.258 


6.553 


20.01 


13009 


NPS 6 


DN 150 


6.625 


168.3 


0.280 


7.112 


28.89 


18786 


NPS 8 


DN200 


8.625 


1219.1 


0.322 


8.179 


50.27 


32530 


NPS 10 


DN250 


10.750 


273.1 


0.365 


9.271 


78.85 


51275 


NPS 12 


DN 300 


12.750 


323.8 


0.375 


9.525 


1 13.1 


73541 


Note: In applying these rules, the area of the pipe is always based upon standard weight pipe and the 
inlet size of the pressure-reducing valve. 





BV 



NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



SB 




Part 1 , Section 9 

Installation — Glossary of Terms 



99 



NATIDNAL BOARD INSPECTION CODE • PART 1 



INSTALLATION 



PART 1, SECTION 9 
INSTALLATION — GLOSSARY OF TERMS 



9.1 



DEFINITIONS 



For the purpose of applying the rules of the 
NBIC, the following terms and definitions shall 
be used herein as applicable to each Part: 

Additional terms and definitions specific to 
DOT Transport Tanks are defined in Part 2, 
Supplement 6. 

A07 Accumulator — A vessel in which the test 
medium is stored or accumulated prior to its 
use for testing. 

A09 Alteration — A change in the item described on 
the original Manufacturer's Data Report which 
affects the pressure containing capability of the 
pressure-retaining item. (See sub-section 3.4.3, 
EXAMPLES OF ALTERATION.) Nonphysical 
changes such as an increase in the maximum al- 
lowable working pressure (internal or external), 
increase in design temperature, or a reduction 
in minimum temperature of a pressure-retaining 
item shall be considered an alteration. 

ANSI — The American National Standards 
Institute. 

ASME Code — The American Society of Me- 
chanical Engineers' Boiler and Pressure Vessel 
Code published by that Society, including 
addenda and Code Cases, approved by the 
associated ASME Board. 

Assembler — An organization who purchases 
or receives from a manufacturer the necessary 
component parts of valves and assembles, 
adjusts, tests, seals, and ships safety or safety 
relief valves at a geographical location, and 
using facilities other than those used by the 
manufacturer. 

Authorized Inspection Agency — 

New Construction: An Authorized Inspection 
Agency is one that is accredited by the National 
Board meeting the qualification 



and duties of NB-360, Criteria for Acceptance 
of Authorized Inspection Agencies for New 
Construction. 

Inservice: An Authorized Inspection Agency 
is either: 

a) a jurisdictional authority as defined in 
the National Board Constitution; or 

b) an entity that is accredited by the Na- 
tional Board meeting NB 369, Quali- 
fications and Duties for Authorized 
Inspection Agencies Performing Inser- 
vice Inspection Activities and Quali- 
fications for Inspectors of Boilers and 
Pressure Vessels; NB-371 , Accreditation 
of Owner-User Inspection Organiza- 
tions (OUIO) or NB-390, For Federal 
Inspection Agencies (FIAs) Performing 
Inservice Inspection Activities. 

Capacity Certification — The verification by the 
National Board that a particular valve design or 
model has successfully completed all capacity 
testing as required by the ASME Code. 

Chimney or Stack — A device or means for 
providing the venting or escape of combustion 
gases from the operating unit. 

Confined Space — Work locations considered A09 
"confined" because their configurations hinder 
the activities of employees who must enter, 
work in, and exit them. A confined space has 
limited or restricted means for entry or exit, 
and it is not designed for continuous employee 
occupancy. Confined spaces include, but are 
not limited to, underground vaults, tanks, stor- 
age bins, manholes, pits, silos, process vessels, 
and pipelines. Regulatory Organizations often 
use the term "permit-required confined space" 
(permit space) to describe a confined space that 
has one or more of the following characteris- 
tics: contains or has the potential to contain 
a hazardous atmosphere; contains a material 
that has the potential to engulf an entrant; has 
walls that converge inward or floors that slope 



i do 



NATIDNAL BDARD INSPECTION CODE • PART 1 



INSTALLATION 



downward and taper into a smaller area which 
could trap or asphyxiate an entrant; or contains 
any other recognized safety or health hazard, 
such as unguarded machinery, exposed live 
wires, or heat stress. Confined space entry re- 
quirements may differ in many locations and 
the Inspector is cautioned of the need to comply 
with local or site- specific confined space entry 
requirements. 

Conversion — 

Pressure Relief Devices: The change of a pres- 
sure relief valve from one capacity-certified 
configuration to another by use of manufac- 
turer's instructions. 

A07 Units of Measure: Changing the numeric value of 
a parameter from one system of units to another. 

Demonstration — A program of maki ng evident 
by illustration, explanation, and completion of 
tasks documenting evaluation of an applicant's 
ability to perform code activities, including the 
adequacy of the appl icant's qual ity program, and 
by a review of the implementation of that program 
at the address of record and/or work location. 



Forced-Flow Steam Generator — A steam gen- 
erator with no fixed steamline and waterline. 

Inspection — A process of review to ensure 
engineering design, materials, assembly, ex- 
amination and testing requirements have been 
met and are compliant with the Code. 

Inspector — See National Board Commis- 
sioned Inspector and National Board Owner- 
User Commissioned Inspector. 

Intervening — Coming between or inserted 
between, as between the test vessel and the 
valve being tested. 

Jurisdiction — A governmental entity with the 
power, right, or authority to interpret and enforce 
law, rules, or ordinances pertaining to boilers, 
pressure vessels, or other pressure-retaining 
items. It includes National Board member juris- 
dictions defined as "jurisdictional authorities." 

Jurisdictional Authority — A member of the 
National Board, as defined in the National 
Board Constitution. 



Dutchman — Generally limited to tube or pipe 
cross-section replacement. The work necessary 
to remove a compromised section of material 
and replace the section with material meet- 
ing the service requirements and installation 
procedures acceptable to the Inspector. Also 
recognized as piecing. 

Examination — In process work denoting the 
act of performing or completing a task of inter- 
rogation of compliance. Visual observations, 
radiography, liquid penetrant, magnetic par- 
ticle, and ultrasonic methods are recognized 
examples of examination techniques. 

Exit — A doorway, hallway, or similar passage 
that will allow free, normally upright unencum- 
bered egress from an area. 

Field — A temporary location, under the control 
of the Certificate Holder, that is used for repairs 
and/or alterations to pressure-retaining items at 
an address different from that shown on the Cer- 
tificate Holder's Certificate of Authorization. 



Lift Assist Device — A device used to apply an 
auxiliary load to a pressure relief valve stem or 
spindle, used to determine the valve set pres- 
sure as an alternative to a full pressure test. 

Manufacturer's Documentation — The docu- 
mentation that includes technical information 
and certification required by the original code 
of construction. 

Mechanical Assembly — The work necessary to ^08 
establish or restore a pressure retaining boundary, 
under supplementary materials, whereby pres- 
sure retaining capability is established through a 
mechanical, chemical, or physical interface, as 
defined under the rules of the NBIC. 

Mechanical Repair Method — A method of A08 
repair, which restores a pressure retaining 
boundary to a safe and satisfactory operat- 
ing condition, where the pressure retaining 
boundary is established by a method other than 
welding or blazing, as defined under the rules 
of the NBIC. 



1 D 1 



NATIONAL BPARD INSPECTION CODE • PART 1 — INSTALLATION 



NBIC — The National Board Inspection Code 
published by The National Board of Boiler and 
Pressure Vessel Inspectors. 

"NR" Certificate Holder — An organization in 
possession of a valid "NR" Certificate of Autho- 
rization issued by the National Board. 

National Board — The National Board of Boiler 
and Pressure Vessel Inspectors. 

National Board Commissioned Inspector — 

An individual who holds a valid and current 
National Board Commission. 

Nuclear Items — Items constructed in accor- 
dance with recognized standards to be used in 
nuclear power plants or fuel processing facilities. 

Original Code of Construction — Documents 
promulgated by recognized national standards 
writing bodies that contain technical require- 
ments for construction of pressure-retaining items 
or equivalent to which the pressure-retaining item 
was certified by the original manufacturer. 

Owner or User — As referenced in lower case 
letters means any person, firm or corporation 
legally responsible for the safe operation of any 
pressure-retaining item. 

Owner-User Inspection Organization — An 

owner or user of pressure-retaining items that 
maintains an established inspection program, 
whose organization and inspection procedures 
meet the requirements of the National Board 
rules and are acceptable to the jurisdiction or 
jurisdictional authority wherein the owner or 
user is located. 

Owner-User Inspector — An individual who 
holds a valid and current National Board 
Owner-User Commission. 

Piecing — A repair method used to remove 
and replace a portion of piping or tubing ma- 
terial with a suitable material and installation 
procedure. 

Pressure-Retaining Stems (PRS) — Any boiler, 
pressure vessel, piping, or material used for 



the containment of pressure, either internal or 
external. The pressure may be obtained from 
an external source, or by the application of 
heat from a direct source, or any combination 
thereof. 

Pressure Test — Prior to initial operation, the 
completed boiler, including pressure piping, 
water columns, superheaters, economizers, 
stop valves, etc., shall be pressure tested in a 
test performed in accordance with the original 
code of construction prior to initial operation 
of an installed unit that is witnessed by an 
Inspector. 

Repair — The work necessary to restore pres- 
sure-retaining items to a safe and satisfactory 
operating condition. 

Re-ending — A method used to join original 
code of construction piping or tubing with 
replacement piping or tubing material for the 
purpose of restoring a required dimension, 
configuration or pressure-retaining capacity. 

Re-rating — See alteration. 

"R" Certificate Holder — An organization in 
possession of a valid "R" Certificate of Autho- 
rization issued by the National Board. 

Safety Relief Valves — A safety relief valve is 
a pressure relief valve characterized by rapid 
opening or pop action, or by opening in propor- 
tion to the increase in pressure over the opening 
pressure, depending on application. 

Settings — Those components and accessories 
required to provide support for the component 
during operation and during any related main- 
tenance activity. 

Shop — A permanent location, the address that 
is shown on the Certificate of Authorization, 
from which a Certificate Holder controls the A07 
repair and/or alteration of pressure-retaining 
items. 

Testing Laboratory — National Board accepted 
laboratory that performs functional and capac- 
ity tests of pressure relief devices. 



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NATIDNAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



Transient — An occurrence that is maintained 
only for a short interval as opposed to a steady 
state condition. 

Velocity Distortion — The pressure decrease 
that occurs when fluid flows past the opening 
of a pressure sensing line. This is a distortion 
of the pressure that would be measured under 
the same conditions for a non or slowly mov- 
ing fluid. 

/; VR" Certificate Holder — An organization in 
possession of a valid "VR" Certificate of Autho- 
rization issued by the National Board. 

Water Head — The pressure adjustment that 
must be taken into account due to the weight 
of test media (in this case, water) that is 0.433 
psi per vertical ft. (10 kPa per m.) added (sub- 
A07 tracted) from the gage pressure for each foot 
the gage is below (above) the point at which 
the pressure is to be measured. 



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NATIONAL BOARD INSPECTION CODE • PART 1 — INSTALLATION 



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